Power line communication system and method

ABSTRACT

A method of communicatively coupling power line communication (PLC) devices to a first and second overhead power line conductor that travel in a substantially parallel physical arrangement and in spaced-apart relation is provided. The method may comprise coupling a first PLC device to the first power line conductor at a first location, coupling a second PLC device to the first power line conductor at a second location for communication with said first PLC device, at least in part, via the first power line conductor, coupling a third PLC device to the second power line conductor at a third location for communication with said first PLC device; and wherein said third location is between said first location and said second location.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/436,778 filed May 13, 2003 (CRNT-0145), which is herein incorporatedby reference. This application is also a continuation-in-part and claimspriority under 35 U.S.C. §120 to U.S. patent application Ser. No.10/315,725 filed Dec. 10, 2002 (CRNT-0139), which also is hereinincorporated by reference.

FIELD OF THE INVENTION

The present invention generally relates to data communications over apower distribution system and more particularly, to a device forfacilitating communications through power lines and method of using thesame.

BACKGROUND OF THE INVENTION

Well-established power distribution systems exist throughout most of theUnited States, and other countries, which provide power to customers viapower lines. With some modification, the infrastructure of the existingpower distribution systems can be used to provide data communication inaddition to power delivery, thereby forming a power line communicationsystem (PLCS). In other words, existing power lines, that already havebeen run to many homes and offices, can be used to carry data signals toand from the homes and offices. These data signals are communicated onand off the power lines at various points in the power linecommunication system, such as, for example, near homes, offices,Internet service providers, and the like.

While the concept may sound simple, there are many challenges toovercome in order to use power lines for data communication. Overheadpower lines are not designed to provide high speed data communicationsand are very susceptible to interference. Additionally, federalregulations limit the amount of radiated energy of a power linecommunication system, which therefore limits the strength of the datasignal that can be injected onto power lines (especially overhead powerlines).

Power distribution systems include numerous sections, which transmitpower at different voltages. The transition from one section to anothertypically is accomplished with a transformer. The sections of the powerdistribution system that are connected to the customers premisestypically are low voltage (LV) sections having a voltage between 100volts(V) and 240V, depending on the system. In the United States, the LVsection typically is about 120V. The sections of the power distributionsystem that provide the power to the LV sections are referred to as themedium voltage (MV) sections. The voltage of the MV section is in therange of 1,000V to 100,000V. The transition from the MV section to theLV section of the power distribution system typically is accomplishedwith a distribution transformer, which converts the higher voltage ofthe MV section to the lower voltage of the LV section.

Power system transformers are one obstacle to using power distributionlines for data communication. Transformers act as a low-pass filter,passing the low frequency signals (e.g., the 50 or 60 Hz) power signalsand impeding the high frequency signals (e.g., frequencies typicallyused for data communication). As such, power line communication systemsface the challenge of communicating the data signals around, or through,the distribution transformers.

Furthermore, up to ten (and sometimes more) customer premises willtypically receive power from one distribution transformer via theirrespective LV power lines. However, all of the customer premises LVpower lines typically are electrically connected at the transformer.Consequently, a power line communications system must be able totolerate the interference produced by many customers. In addition, thepower line communication system should provide bus arbitration androuter functions for numerous customers who share a LV connection (i.e.,the customer premises LV power lines that are all electrically connectedto the LV power line extending from the LV side of the transformer) anda MV power line.

In addition, components of the power line communication system, such asthe distribution transformer bypass device (BD), must electricallyisolate the MV power signal from the LV power lines and the customerpremises. In addition, a communication device of the system should bedesigned to facilitate bi-directional communication and to be installedwithout disrupting power to customers. These and other advantages areprovided by various embodiments of the present invention.

SUMMARY OF THE INVENTION

The present invention provides a method of communicatively couplingpower line communication (PLC) devices to multiple overhead power lineconductors that travel in a substantially parallel physical arrangementand in spaced-apart relation is provided. In one embodiment, the methodmay comprise coupling a first PLC device to the first power lineconductor at a first location, coupling a second PLC device to the firstpower line conductor at a second location for communication with saidfirst PLC device, at least in part, via the first power line conductor,coupling a third PLC device to the second power line conductor at athird location for communication with said first PLC device; and whereinsaid third location is between said first location and said secondlocation.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described in the detailed description thatfollows, by reference to the noted drawings by way of non-limitingillustrative embodiments of the invention, in which like referencenumerals represent similar parts throughout the drawings. As should beunderstood, however, the invention is not limited to the precisearrangements and instrumentalities shown. In the drawings:

FIG. 1 is a diagram of an exemplary power distribution system with whichthe present invention may be employed;

FIG. 2 is a diagram of the exemplary power distribution system of FIG. 1modified to operate as a power line communication system, in accordancewith an embodiment of the present invention;

FIG. 3 is a schematic of a power line communication system in accordancewith an embodiment of the present invention;

FIG. 4 is a block diagram of a bypass device, in accordance with anembodiment of the present invention;

FIG. 5 is a block diagram of a bypass device, in accordance with anembodiment of the present invention;

FIGS. 6 a-c is a functional block diagram of a portion of a bypassdevice, in accordance with an embodiment of the present invention;

FIG. 7 is a schematic of a portion of a medium voltage interface for usein an embodiment of the present invention;

FIG. 8 is a schematic of a portion of an alternate medium voltageinterface for use in an embodiment of the present invention;

FIG. 9 is a functional block diagram illustrating of a portion of abypass device, in accordance with an embodiment of the presentinvention;

FIG. 10 is a functional block diagram of a bypass device, in accordancewith another embodiment of the present invention;

FIG. 11 is a schematic of backhaul point in a power line communicationsystem, in accordance with an embodiment of the present invention;

FIG. 12 is a diagram of a power distribution system modified to operateas a power line communication system, in accordance with anotherembodiment of the present invention;

FIG. 13 is a functional block diagram of a bypass device, in accordancewith another embodiment of the present invention;

FIG. 14 is a functional block diagram of a communication device, inaccordance with another embodiment of the present invention;

FIG. 15 is a schematic of a portion of a power line communication systemin accordance with an embodiment of the present invention;

FIG. 16 is a schematic of a portion of a power line communication systemin accordance with another embodiment of the present invention; and

FIGS. 17 a-b are schematics of a portion of a power line communicationsystem in accordance an embodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In the following description, for purposes of explanation and notlimitation, specific details are set forth, such as particular networks,communication systems, computers, terminals, devices, components,techniques, data and network protocols, software products and systems,operating systems, development interfaces, hardware, etc. in order toprovide a thorough understanding of the present invention.

However, it will be apparent to one skilled in the art that the presentinvention may be practiced in other embodiments that depart from thesespecific details. Detailed descriptions of well-known networks,communication systems, computers, terminals, devices, components,techniques, data and network protocols, software products and systems,operating systems, development interfaces, and hardware are omitted soas not to obscure the description of the present invention.

System Architecture and General Design Concepts

As shown in FIG. 1, power distribution systems typically includecomponents for power generation, power transmission, and power delivery.A transmission substation typically is used to increase the voltage fromthe power generation source to high voltage (HV) levels for longdistance transmission on HV transmission lines to a substation. Typicalvoltages found on HV transmission lines range from 69 kilovolts (kV) toin excess of 800 kV.

In addition to HV transmission lines, power distribution systems includeMV power lines and LV power lines. As discussed, MV typically rangesfrom about 1000 V to about 100 kV and LV typically ranges from about 100V to about 240 V. Transformers are used to convert between therespective voltage portions, e.g., between the HV section and the MVsection and between the MV section and the LV section. Transformers havea primary side for connection to a first voltage (e.g., the MV section)and a secondary side for outputting another (usually lower) voltage(e.g., the LV section). Such transformers are often referred to asdistribution transformers or a step down transformers, because they“step down” the voltage to some lower voltage. Transformers, therefore,provide voltage conversion for the power distribution system. Thus,power is carried from substation transformer to a distributiontransformer over one or more MV power lines. Power is carried from thedistribution transformer to the customer premises via one or more LVpower lines.

In addition, a distribution transformer may function to distribute one,two, three, or more phase currents to the customer premises, dependingupon the demands of the user. In the United States, for example, theselocal distribution transformers typically feed anywhere from one to tenhomes, depending upon the concentration of the customer premises in aparticular area. Distribution transformers may be pole-top transformerslocated on a utility pole, pad-mounted transformers located on theground, or transformers located under ground level.

The communication device of the present invention may form part of aPLCS to communicate signals to and from communication devices at thecustomer premises through the LV power line. In addition, thecommunication device of the present invention may facilitate thecommunication of data signals along the MV power line with 1) otherpower line communication devices; 2) one or more backhaul points; 3) oneor more power line servers; and/or 4) devices on a network such as theInternet.

Power Line Communication System

One example of such a PLCS is shown in FIG. 2 and includes one or morebypass devices 100, which may be formed by an embodiment of the presentinvention. In this example, the present invention is embodied as abypass device 100 to communicate data signals around the distributiontransformer that would otherwise filter such data signals, preventingthem from passing through the transformer. Thus, the communicationdevice in this embodiment is a BD 100 that is the gateway between the LVpower line subnet (i.e., the devices that are communicatively coupled tothe LV power lines) and the MV power line.

In this embodiment, the BD the provides communication services for theuser, which may include security management, routing of Internetprotocol (IP) packets, filtering data, access control, service levelmonitoring, signal processing and modulation/demodulation of signalstransmitted over the power lines.

This example PLCS also includes a backhaul point 10, which may also bean alternate embodiment of the present invention. The backhaul point 10is an interface and gateway between a PLCS and a traditional non-powerline telecommunication network. One or more backhaul points 10 arecommunicatively coupled to an aggregation point (AP) 20 that in manyembodiments may be the point of presence to the Internet. The backhaulpoint 10 may be connected to the AP 20 using any available mechanism,including fiber optic conductors, T-carrier, Synchronous Optical Network(SONET), or wireless techniques well known to those skilled in the art.Thus, the backhaul point 10 may include a transceiver suited forcommunicating through the communication medium.

The AP 20 may include a conventional Internet Protocol (IP) data packetrouter and may be directly connected to an Internet backbone therebyproviding access to the Internet. Alternatively, the AP 20 may beconnected to a core router (not shown), which provides access to theInternet, or other communication network. Depending on the configurationof the PLCS, a plurality of APs 20 may be connected to a single corerouter which provides Internet access. The core router (or AP 20 as thecase may be) may route voice traffic to and from a voice serviceprovider and route Internet traffic to and from an Internet serviceprovider. The routing of packets to the appropriate provider may bedetermined by any suitable means such as by including information in thedata packets to determine whether a packet is voice. If the packet isvoice, the packet may be routed to the voice service provider and, ifnot, the packet may be routed to the Internet service provider.Similarly, the packet may include information (which may be a portion ofthe address) to determine whether a packet is Internet data. If thepacket is Internet data, the packet may be routed to the Internetservice provider and, if not, the packet may be routed to the voiceservice provider.

In some PLCS embodiments, there may a distribution point (not shown)between the backhaul point 10 and the AP 20. The distribution point,which may be a router, may be coupled to a plurality of backhaul points10 and provides routing functions between its backhaul points 10 and itsAP 20. In one example embodiment, a plurality of backhaul points 10 areconnected to each distribution point and each distribution point (ofwhich there is a plurality) is coupled to the AP 20, which providesaccess to the Internet.

The PLCS also may include a power line server (PLS) that is a computersystem with memory for storing a database of information about the PLCSand includes a network element manager (NEM) that monitors and controlsthe PLCS. The PLS allows network operations personnel to provision usersand network equipment, manage customer data, and monitor system status,performance and usage. The PLS may reside at a remote operations centerto oversee a group of communication devices via the Internet. The PLSmay provide an Internet identity to the network devices by assigning thedevices (e.g., user devices, BDs 100, (e.g., the LV modems and MV modemsof BDs), repeaters 70, backhaul points 10, and AP 20) an IP address andstoring the IP address and other device identifying information (e.g.,the device's location, address, serial number, etc.) in its memory. Inaddition, the PLS may approve or deny user devices authorizationrequests, command status reports and measurements from the BDs,repeaters, and backhaul points, and provide application softwareupgrades to the communication devices (e.g., BDs, backhaul points,repeaters, and other devices). The PLS, by collecting electric powerdistribution information and interfacing with utilities' back-endcomputer systems may provide enhanced distribution services such asautomated meter reading, outage detection, load balancing, distributionautomation, Volt/Volt-Amp Reactance (Volt/VAr) management, and othersimilar functions. The PLS also may be connected to one or more APsand/or core routers directly or through the Internet and therefore cancommunicate with any of the BDs, repeaters, user devices, and backhaulpoints through the respective AP and/or core router.

At the user end of the PLCS, data flow originates from a user device,which provides the data to a power line interface device (PLID) 50(sometimes referred to as a power line modem), which is well-known inthe art.

Various electrical circuits within the customer's premises distributepower and data signals within the customer premises. The customer drawspower on demand by plugging a device into a power outlet. In a similarmanner, the customer may plug the PLID 50 into a power outlet todigitally connect user devices to communicate data signals carried bythe power wiring. The PLID 50 thus serves as an interface for userdevices to access the PLCS. The PLID 50 can have a variety of interfacesfor customer data appliances. For example, a PLID 50 can include a RJ-11Plain Old Telephone Service (POTS) connector, an RS-232 connector, a USBconnector, a 10 Base-T connector, RJ-45 connector, and the like. In thismanner, a customer can connect a variety of user devices to the PLCS.Further, multiple PLIDs can be plugged into power outlets throughout thecustomer premises, with each PLID 50 communicating over the same wiringinternal to the customer premises.

The user device connected to the PLID 50 may be any device cable ofsupplying data for transmission (or for receiving such data) including,but not limited to a computer, a telephone, a telephone answeringmachine, a fax, a digital cable box (e.g., for processing digital audioand video, which may then be supplied to a conventional television andfor transmitting requests for video programming), a video game, astereo, a videophone, a television (which may be a digital television),a video recording device, a home network device, a utility meter, orother device. The PLID 50 transmits the data received form the userdevice through the customer LV power line to a BD 100 and provides datareceived from the LV power line to the user device. The PLID 50 may alsobe integrated with the user device, which may be a computer. Inaddition, the functions of the PLID may be integrated into a smartutility meter such as a gas meter, electric meter, water meter, or otherutility meter to thereby provide automated meter reading (AMR).

The BD 100 typically transmits the data to the backhaul point 10, which,in turn, transmits the data to the AP 20. The AP 20 then transmits thedata to the appropriate destination (perhaps via a core router), whichmay be a network destination (such as an Internet address) in which casethe packets are transmitted to, and pass through, numerous routers(herein routers are mean to include both network routers and switches)in order to arrive at the desired destination.

FIG. 3 illustrates a power distribution network topology providing oneexample of a portion of a PLCS employing the present invention. Thepower distribution network shown in FIG. 3 includes three MV phaseconductors. Each of the three MV phase conductors is connected to one ormore distribution transformers 60. Each distribution transformer 60 mayinclude an associated BD 100, although if no users receiving power fromthe distribution transformer subscribe to the PLCS service, thedistribution transformer may not have an associated BD. Each BD 100 iscoupled to the MV power line and the LV power line connected to thetransformer 60, thereby providing a path for data around the transformer60. Each customer premises 40 may include one or more PLIDs 50 and oneor more user devices 80. Those users who are not subscribers to thecommunication service may not have a PLID 50 or user device 80 connectedto the PLCS. Depending on the power distribution system, there may beten or more customer premises 40 coupled to a single distributiontransformer 60.

If the backhaul point 10 and the BD 100 are too far apart (along the MVpower line), noise and interference may prevent reliable communicationstherebetween. Thus, the PLCS may have a maximum communication distance(MCD) (along the MV line) over which the backhaul point 10 and BD 100may communicate reliably. However, sometimes a distribution transformer60 and its BD 100 may be located more than the MCD away from thebackhaul point 10.

To overcome this problem, the PLCS may use BDs 100 located along the MVline as a repeater to repeat and/or amplify data. For example, if BD 100c is more than the MCD from the backhaul point 10, BD 100 b may repeat(i.e., receive and transmit on the MV line) data received from thebackhaul point 10 that is intended for BD 100 c (or alternately repeatall data received on the MV line that is not intended for BD 100 b orits subnet). Similarly, BD 100 b may repeat data received from BD 100 cthat is intended for backhaul point 10 or alternately repeat all datareceived on the MV line that is not received from the backhaul point 10or that is not intended for BD 100 b or its LV subnet.

If there are no BDs 100 disposed between the backhaul point 10 and a BD100 that is out of communication range of the backhaul point 10, it maybe necessary to include a repeater therebetween. As shown on phase 2 ofthe MV line, a repeater 70 is disposed between the backhaul point 10 andBD 100 a. While the repeater does not necessarily need not be near adistribution transformer, it may be more practical to install it near adistribution transformer (e.g., attached to the same pole) to allow therepeater to draw power from the LV power line extending from thetransformer. Alternatively, the repeater—because it does not need tocouple data to the LV power line—may be a self-contained device thatcouples to the MV line to draw power therefrom and communicate datatherewith, thereby alleviating the need to provide electrical isolationfrom the LV power line. The repeater 70 may function to repeat data in amanner similar to that described above with respect to the BD 100 b ormay repeat all data received.

The backhaul point 10 of FIG. 3 is shown coupled to each phase of the MVpower line. In practice, however, this may not be necessary. In someembodiments, such as those communicating through overhead MV conductors,data signals may couple across the MV conductors. In other words, datasignals transmitted on one MV phase conductor may be present on all ofthe MV phase conductors due to the data coupling between the conductors.As a result, the backhaul point 10 may not need to be physicallyconnected to all three phase conductors of the MV cable and transmissionfrom the backhaul point 10 when coupled to one MV phase conductor willbe received by the BDs 100 connected to the other MV phase conductorsand vice versa. In some embodiments, however, which may includeunderground MV cables, it may be desirable to couple the backhaul point10 to all of the available phase conductors.

Bypass Device Embodiment

The following description is for a communication device of the presentinvention that is embodied as a BD. In particular, the embodimentdescribed immediately below is a BD for bypassing a pole-mountedtransformer. The present invention is equally applicable for use inbypassing other types of transformers (such as pad mount andunderground) and in other applications (such as repeaters and backhaulpoints) with minor modifications that will be evident to those skilledthe art. The BD may provide a path for data to bypass the transformer bybeing coupled to the same MV power line conductor that the transformeris coupled or to a different MV power line conductor and, in eitherinstance, may be coupled to the same LV power lines to which thetransformer is coupled.

The BD described herein, which is an example embodiment of the presentinvention, provides bi-directional communications and includes thefunctional block diagrams shown in FIG. 4. In particular, in thisembodiment of the BD 100 includes a MV power line interface (MVI) 200, acontroller 300, and a LV power line interface (LVI) 400. The BD 100 iscontrolled by a programmable processor and associated peripheralcircuitry, which form part of the controller 300. The controller 300includes memory that stores, among other things, program code, whichcontrols the operation of the processor.

Referring to FIG. 5, the LVI 400 may include a LV power line coupler410, a LV signal conditioner 420, and a LV modem 450. The router 310forms part of the controller 300 and performs routing functions. Router310 may perform routing functions using layer 3 data (e.g., IPaddresses), layer 2 data (e.g., MAC addresses), or a combination oflayer 2 and layer 3 data (e.g., a combination of MAC and IP addresses).The MVI 200 may include a MV modem 280, a first MV signal conditioner260, an isolator 240, a second MV signal conditioner 220, and a powerline coupler 210. In addition to routing, the controller 300 may performother functions including controlling the operation of the LVI 400 andMVI 200 functional components. A more complete description of thecontroller 300 and its functionality is described below.

As discussed, this embodiment of the present invention providesbi-directional communications around the distribution transformer 60 tothereby provide a first communications path from the LV power line tothe MV power line and a second path from the MV power line to the LVpower line. For ease of understanding, the processing, and functionalcomponents of a communication path from the LV power line to the MVpower line (the LV to MV path) will be described first. Subsequently,the processing and functional components of the communication path fromthe MV power line to the LV power line (the MV to LV path) will bedescribed.

As will be evident to those skilled in the art, the two paths arelogical paths. The LV to MV path and the MV to LV path may be separatephysical electrical paths at certain functional blocks and may be thesame physical path in other functional blocks. However, otherembodiments of the present invention may provide for a completely, orsubstantially complete, separate physical path for the LV to MV and theMV to LV paths.

LV Power Line to MV Power Line Path

In the United States, the LV power line typically includes a neutralconductor and two conductors carrying current (“energized”) conductors.In the United States, the two energized conductors typically carry about120V alternating current (AC) at a frequency of 60 Hz and are 180degrees out of phase with each other. The present invention is suitablefor LV power line cables having conductors that are spaced apart or thatare coupled together (e.g., in a twisted pair or via the conductorinsulation).

LV Coupler

The LVI 400 includes a LV power line coupler 410 that couples data toand from the LV power line and may include a transducer. The coupler 410also may couple power from the LV power line, which is used to power atleast a portion of the BD 100. In this embodiment, the electronics ofmuch of the BD 100 is housed in an enclosure with first and second BDcables extending from the enclosure. The first BD cable includes atwisted pair of conductors including a signal conductor and neutralconductor. The first conductor of the first BD cable is connected to oneof the energized LV conductors extending from the transformer and thesecond conductor of the first BD cable is connected to the neutralconductor extending from the transformer. In this embodiment, clampingthe BD conductors to the LV power line conductors makes the connection.

The second BD cable extending from the enclosure is also a twisted paircomprised of a first and second conductor. The first conductor of thesecond BD cable is connected to the neutral conductor extending from thetransformer and the second conductor of the second BD cable is connectedto the second (other) energized LV conductor extending from thetransformer.

The third BD cable is a ground conductor that may be connected to anearth ground, which typically is an earth ground conductor that connectsthe transformer housing to a ground rod. The neutral conductor of the LVpower line may also be connected to the earth ground of the power linesystem (by the electric power company). However, their may be anintrinsic RF impedance between the BD ground conductor connection andthe LV neutral conductor connections of the BD (i.e., the secondconductor of the first BD cable and the first conductor of the second BDcable). Additionally, it may be desirable to add an RF impedance (e.g.,an RF choke) between the connections.

In other embodiments, the LV coupler 410 may include a transducer andmay be an inductive coupler such as toroid coupling transformer or acapacitive coupler, for coupling data to and/or from the LV power lineand/or for coupling power from the LV power line.

In this embodiment, the signals entering the BD 100 via the first andsecond BD cables (hereinafter the first signal and second signalrespectively) are processed with conventional transient protectioncircuitry, which is well-known to those skilled in the art. Next, thefirst signal and second signal are processed with voltage translationcircuitry. The data signals in this embodiment, which are in the 4.5 to21 MHz band, “ride on” (i.e., are additive of) the low frequency powersignal (the 120V 60 Hz voltage signal). Consequently, in thisembodiment, it is desirable to remove the low frequency power signal,but to keep the data signals for processing, which is accomplished bythe voltage translation circuitry. The voltage translation circuitry mayinclude a high pass filter to remove the low frequency power signal andmay also (or instead) include other conventional voltage translationcircuitry.

Next, the first and second signals may be processed with impedancetranslation circuitry, which is well-known in the art. In thisembodiment, it is desirable to substantially match the impedance of theLV power line. One method of matching the impedance of the LV power lineis to separately terminate the BD LV conductors of the first and secondBD cables through a termination resistor to ground. The value of thetermination resistor may be selected to match the characteristicimpedance of the LV power line.

The electronics of the BD 100 that are on the LV side of the isolator240 may be powered by power received from the LV power line. Thus, thisembodiment of the BD 100 includes a power supply for powering much ofthe BD 100 electronics. The power supply may include its own transientprotection circuitry, which may be in addition to, or instead of, thetransient protection circuitry that processes the data signals describedabove. Thus, the power supply may receive power from the BD LV conductorof the first (or second) BD cable after the power signal passes throughthe transient protection circuitry.

In addition to the power supply, the BD 100 may include a battery backupfor operating the BD 100 during power outages. Thus, a backup powersystem (which may include a battery) may allow the device to detect apower outage and communicate information relating to the outage to theutility company and/or PLS. In practice, information of the outage maybe transmitted to the PLS, which communicates the location, time, and/orother information of the outage to the power utility (e.g., theutility's computer system). The backup power system also may allow theBD 100 to communicate certain data packets during a power outage. Forexample, during an outage, the BD 100 may be programmed to communicateall voice data or only emergency voice transmissions (e.g., phone callsdialed to 911).

LV Signal Conditioner

Once the LV power line coupler 410 couples the signals (both power anddata) from the LV power line, the data signals are provided to the LVsignal conditioner 420. In this example embodiment, the BD 100 mayeither transmit data to, or receive data from, the LV power line at anyone instant. From the user's perspective, however, the communicationsmay seem simultaneous because the change in direction of data flow (fromtransmit to receive and vice versa) is very fast and transmission andreception is contemporaneous over very short periods of time.

FIG. 6 is a block diagram of a portion of a bypass device. The processorof the controller 300 controls a set of switches 426 (e.g., Field-effectTransistor (FET) switches), which when in a first configuration permitreception and when in a second configuration permit transmission therebyproviding a fast LV transmit/receive switch 426 for communicatingthrough the LV power lines.

In this embodiment, the LV data signals are in the frequency band ofapproximately 4.5 to 21 MHz and, as discussed, the data signals “rideon” the low frequency power signal. As a result, even though the twoenergized LV conductors typically are kept separate electrically, thereis significant coupling of data signals between the energized LVconductors at these frequencies. Consequently, a signal sent on oneenergized LV conductor from the customer premises typically will bepresent on both energized LV conductors at the BD 100.

The LV power line often does not, however, have a flat frequencyresponse over the frequency band of the data signals, which isespecially true for underground power distribution system cables. Morespecifically, LV power lines sometimes have a greater loss at higherfrequencies than at lower frequencies. To compensate for thenonlinearity of the LV power line communication channel, this embodimentof the present invention provides separate, and potentially different,signal processing for the higher frequencies.

As shown in FIG. 6 a, after passing through the LV transmit/receiveswitch 426 (which would be in receive mode) the first signal (comprisingdata signals from the BD LV conductor of the first cable) is supplied toa first filter 421 a that has a pass band of approximately 4.0 to 10MHz. The second signal (comprising data signals from the BD LV conductorof the second BD cable) is supplied to a second filter 421 b that has apass band of approximately 10-21 MHz. Each of these filters 421 providespass band filtering and may also provide anti-aliasing filtering fortheir respective frequency bands, and noise filtering.

The outputs of the first and second filters 421 a-b are supplied to afirst amplifier 422 a and second amplifier 422 b, respectively. Theoutputs of the first and second amplifiers 422 a-b are coupled to afirst feedback device 423 a and a second feedback device 423 b,respectively. Each feedback device 423 measures the power over time andsupplies the power measurement to the controller 300. Based on the powermeasurement, the controller 300 increases, decreases, or leaves the gainof the associated amplifiers the same to provide automatic gain control(AGC). The outputs of the first and second amplifiers 422 are alsosupplied to a summation device 424 that sums the two pass band,amplified signals to provide a single data signal.

Thus, the gain of the second amplifier 422 b, which receives signals inthe 10-21 MHz band, may be greater (or may be dynamically made greater)than the gain of the first amplifier 422 a, which receives signals inthe 4.5 to 10 MHz band. The higher gain of the second amplifier filter422 b can thus compensate for the greater loss of the transmissionchannel at the higher frequencies.

In this embodiment, the amplification by the amplifiers 422 isaccomplished by amplifying the signal a first predetermined amount,which may be the same or different (e.g., such as proportional to theanticipated loss of the channel) for each amplifier. The amplifiedsignal is then attenuated so that the resultant amplified andsubsequently attenuated signal is at the appropriate amplification withrespect to the original signal, which may be determined by controller300 from information received by the feedback devices 423. The feedbackdevice 423 may be implemented with suitable feedback architecture,well-known to those skilled in the art. For example, the feedbackdevices 423 may use both hardware (such as feedback that may be providedby an analog to digital converter) and software (such as in modifyingthe reference voltage supplied to an operational amplifier that isimplementing amplifier 422).

Other embodiments may not include filtering the inputs of the two BD LVconductors at separate pass bands and separately amplifying the filteredsignals. Instead, the signal may be filtered and amplified across theentire LV power line communication pass band (e.g., from 4.5 to 21 MHz).Similarly, while this embodiment divides the LV power line communicationchannel into two bands (for filtering, amplifying and summing), otherembodiments may similarly divide the LV power line communication channelinto three, four, five or more bands (for filtering, amplifying andsumming).

LV Modem

The output of the summing device of the LV signal conditioner 420 issupplied to the LV modem 450, which includes a modulator anddemodulator. The LV modem 450 also may include one or more additionalfunctional submodules such as an Analog-to-Digital Converter (ADC),Digital-to-Analog Converter (DAC), a memory, source encoder/decoder,error encoder/decoder, channel encoder/decoder, MAC (Media AccessControl) controller, encryption module, and decryption module. Thesefunctional submodules may be omitted in some embodiments, may beintegrated into a modem integrated circuit (chip or chip set), or may beperipheral to a modem chip. In the present example embodiment, the LVmodem 450 is formed, at least in part, by part number INT5130, which isan integrated power line transceiver circuit incorporating most of theabove-identified submodules, and which is manufactured by Intellon, Inc.of Ocala, Fla.

The incoming signal from the summation device 424 is supplied to the ADCto convert the incoming analog signal to a digital signal. The digitalsignal is then demodulated. The LV modem 450 then provides decryption,source decoding, error decoding, channel decoding, and media accesscontrol (MAC) all of which are known in the art and, therefore, notexplained in detail here.

With respect to MAC, however, the LV modem 450 may examine informationin the packet to determine whether the packet should be ignored orpassed to the router 310. For example, the modem 450 may compare thedestination MAC address of the packet with the MAC address of the LVmodem 450 (which is stored in the memory of the LV modem 450). If thereis a match, the LV modem 450 removes the MAC header of the packet andpasses the packet to the router 310. If there is not a match, the packetmay be ignored.

Router

The data packet from the LV modem 450 may be supplied to the router 310,which forms part of the controller 300. The router 310 performsprioritization, filtering, packet routing, access control, andencryption. The router 310 of this example embodiment of the presentinvention uses a table (e.g., a routing table) and programmed routingrules stored in memory to determine the next destination of a datapacket. The table is a collection of information and may includeinformation relating to which interface (e.g., LVI 400 or MVI 200) leadsto particular groups of addresses (such as the addresses of the userdevices connected to the customer LV power lines), priorities forconnections to be used, and rules for handling both routine and specialcases of traffic (such as voice packets and/or control packets).

The router 310 will detect routing information, such as the destinationaddress (e.g., the destination IP address) and/or other packetinformation (such as information identifying the packet as voice data),and match that routing information with rules (e.g., address rules) inthe table. The rules may indicate that packets in a particular group ofaddresses should be transmitted in a specific direction such as throughthe LV power line (e.g., if the packet was received from the MV powerline and the destination IP address corresponds to a user deviceconnected to the LV power line), repeated on the MV line (e.g., if theBD 100 is acting as a repeater), or be ignored (e.g., if the addressdoes not correspond to a user device connected to the LV power line orto the BD 100 itself).

As an example, the table may include information such as the IPaddresses (and potentially the MAC addresses) of the user devices on theBD's LV subnet, the MAC addresses of the PLIDs 50 on the BD's LV subnet,the MV subnet mask (which may include the MAC address and/or IP addressof the BD's backhaul point 10), and the IP address of the LV modem 450and MV modem 280. Based on the destination IP address of the packet(e.g., an IP address), the router may pass the packet to the MV modem280 for transmission on the MV power line. Alternately, if the IPdestination address of the packet matches the IP address of the BD 100,the BD 100 may process the packet as a request for data.

In other instances, such as if the user device is not provisioned andregistered, the router may prevent packets from being transmitted to anydestination other than a DNS server or registration server. In addition,if the user device is not registered, the router 310 may replace anyrequest for a web page received from that user device with a request fora web page on the registration server (the address of which is stored inthe memory of the router).

The router 310 may also prioritize transmission of packets. For example,data packets determined to be voice packets may be given higher priorityfor transmission through the BD than data packets so as to reduce delaysand improve the voice connection experienced by the user. Routing and/orprioritization may be based on IP addresses, MAC addresses, subscriptionlevel, or a combination thereof (e.g., the MAC address of the PLID or IPaddress of the user device).

MV Modem

Similar to the LV modem 450, the MV modem 280 receives data from therouter 310 and includes a modulator and demodulator. In addition, the MVmodem 280 also may include one or more additional functional submodulessuch as an ADC, DAC, memory, source encoder/decoder, errorencoder/decoder, channel encoder/decoder, MAC controller, encryptionmodule, and decryption module. These functional submodules may beomitted in some embodiments, may be integrated into a modem integratedcircuit (chip or chip set), or may be peripheral to a modem chip. In thepresent example embodiment, the MV modem 280 is formed, at least inpart, by part number INT5130, which is an integrated power linetransceiver circuit incorporating most of the identified submodules andwhich is manufactured by Intellon, Inc. of Ocala, Fla.

The incoming signal from the router 310 (or controller) is supplied tothe MV modem 280, which provides MAC processing, for example, by addinga MAC header that includes the MAC address of the MV modem 280 as thesource address and the MAC address of the backhaul point 10 (and inparticular, the MAC address of the MV modem of the backhaul point) asthe destination MAC address. In addition, the MV modem 280 also provideschannel encoding, source encoding, error encoding, and encryption. Thedata is then modulated and provided to the DAC to convert the digitaldata to an analog signal.

First MV Signal Conditioner

The modulated analog signal from MV modem 280 is provided to the firstMV signal conditioner 260, which may provide filtering (anti-alias,noise, and/or band pass filtering) and amplification. In addition, theMV signal conditioner 260 may provide frequency translation. In thisembodiment, the translation is from the 4-21 MHz band of the LV powerline to the band of the MV power line, which in this embodiment is ahigher frequency band. In this embodiment, translation of the frequencyis accomplished through the use of a local oscillator and a conversionmixer. This method and other methods of frequency translation are wellknown in the art and, therefore, not described in detail.

As is known in the art, frequency translation may result in a first andsecond image of the original frequency although in some instances, suchas in the present embodiment, only one of the two images is desired.Thus, the frequency translation circuitry may include an image rejectionfilter to filter out the undesired image leaving only the desiredfrequency bandwidth, which in this embodiment is the higher frequencyband of the MV power line.

Isolator

The isolator 240 of the present embodiment provides isolation for boththe LV to MV path and the MV to LV path that is substantially the same.The isolator 240 provides electrical isolation between the MV power lineand the LV power line, thereby ensuring that the higher voltages of theMV power line do not reach the LV power line or the customer premises.In addition, the isolator 240 in this embodiment ensures that thevoltages of the MV power line do not reach the electronics on the LVside of the isolator 240, which may be referenced to the neutral of theLV power line.

The output of the MV first signal conditioner 260 may be supplied to theisolator 240, which may be a fiber optic isolator comprising a fiberoptic transmitter (or transceiver) on the LV side of the isolator 240and a fiber optic receiver (or transceiver) on the MV side of theisolator 240. Hereinafter, a fiber optic transmitter (or receiver) shallinclude a transmitter (or receiver) that forms part of a fiber optictransceiver. The fiber optic transmitter and fiber optic receiver (ortransceivers) are communicatively coupled through a fiber opticconductor(s) or light pipe(s). While this embodiment employs a fiberoptic based isolator, other embodiments may use an inductive isolator(such as in a transformer), a capacitive isolator, a wireless isolatorpath (such as a Bluetooth® wireless path, an 802.11 wireless path, or anultrawideband wireless path), or some combination thereof.

The isolator 240 also may include isolation signal conditioningcircuitry that filters (e.g., band pass, anti-aliasing, noise),amplifies, and/or performs other processing or conditioning of thesignal, which may be necessary for interfacing the isolator with thesurrounding components of the device. The isolation signal conditioningcircuitry may be on the LV side of the isolator and/or on the MV side ofthe isolator 240. While the isolator in this embodiment forms part ofthe MVI 200, the isolator may instead form part of the LVI 400.

Second MV Signal Conditioner

The isolator 240 supplies the signals to the second MV signalconditioner 220 on the MV side of the isolator 240. The second MV signalconditioner 220 may condition the signal by filtering and/or amplifyingthe signal. In addition, the signal may buffer the signal and provideload balancing.

The output of these conditioning elements may be supplied to a MVtransmit/receive switch (not shown), which controls whether the BD 100is transmitting or receiving on the MV power line. The MVtransmit/receive switch may default to receive mode so that datareceived from the MV line will pass through the switch to the receivecircuitry. The MV transmit/receive switch also may be coupled to atransmission detection circuit, which detects when data is beingprovided for transmission on the MV line from the router 310 (forexample, which may have originated from a user device). When thetransmission detect circuitry detects transmission data, the circuitrytransitions the switch to transmit mode so that the data to betransmitted may pass through the MV transmit/receive switch to the MVpower line.

MV Power Coupler Line

Data passing through the MV transmit/receive switch for transmission onthe MV power line is supplied to the MV power line coupler 210, whichmay include impedance translation circuitry, transient suppressioncircuitry, and a coupling device. The coupling device couples the dataonto the MV power line as a transmission.

The coupling device may be inductive, capacitive, conductive, acombination thereof, or any suitable device for communicating datasignals to and/or from the MV power line. One example of such a coupleris described in U.S. application Ser. No. 10/176,500, entitled “PowerLine Coupling Device and Method of Using the Same,” which is herebyincorporated by reference.

As explained in detail in that application, from an electricalperspective the coupling device includes a data filter which may beradio frequency (RF) filter or RF choke 705 communicatively coupled tothe MV power line between the connection nodes as shown in FIG. 7. TheRF choke 705 provides the impedance with inductors (e.g., ferritetoroids) disposed in the inductor chambers of a housing. Inductances mayrange from about 0.1 microHenries to 5.0 microHenries.

The RF choke 705 operates as a low pass filter. In other words, lowfrequency signals (e.g., having a frequency of 50 or 60 Hz) of the MVpower signal pass through the RF choke relatively unimpeded (i.e., theRF choke can be modeled as a short circuit to low frequency signals).High frequency signals (e.g., a data signal), however, do not passthrough RF choke; rather, they are impeded by the RF choke 705 (i.e.,the RF choke 705 can be modeled as a high impedance circuit to highfrequency signals). As such, the voltage across the RF choke 705includes data signals but substantially no power signals. This voltage(i.e., the voltage across the RF choke 705) is applied to transformer720 via capacitors 710 to receive data signals from MV power line. Totransmit data signals to the MV power line, a data signal is applied totransformer 720, which in turn communicates the data signal to MV powerline through capacitors 710.

The impedance translation circuitry and transient suppression circuitryof this MV coupler is provided, at,least in part, by capacitors 710 andtransformer 720. Capacitors 710 provide some electrical isolationbetween MV power line and transformer 720. Capacitors 710 furtherprovide filtering of stray power signals. That is, the data signalpasses across capacitors 710 while any lower frequency power signals aresubstantially prevented from passing across capacitors 710.

Transformer 720 may operate as a differential transceiver. That is,transformer 720 may operate to repeat data signals received from the MVpower line to receive circuitry 612 and to repeat data signals receivedfrom transmit circuitry 610 to the MV power line. Transformer 720 alsoprovides some electrical isolation between MV power line and LV powerline. Transformer 720 also permits RF signals, such as data signals, topass through and travel on down the power line.

Also shown in FIG. 7, this coupling device is coupled to an isolator 240comprised of a fiber optic transceiver. Capacitors 606 are electricallyconnected between transmit circuitry 610 and receive circuitry 612 andtransformer 720. Transmit circuitry 610 and receive circuitry 612 areelectrically connected to transmit optoelectronic device 620 and receiveoptoelectronic device 622, respectively. Transmit optoelectronic device620 (e.g., a photo diode) and receive optoelectronic device 622 (e.g., aphoto detector) collectively form a transceiver and are in communicationwith communication medium 630, which acts as an isolator.

In the embodiment illustrated in FIG. 7, the communication medium 630 ofthe isolator is a fiber optic cable that provides electrical powerisolation between MV power line and LV power line. In this exampleembodiment, power may be supplied to the MV side of the isolator 240 viaa power supply that includes a transducer (e.g., a photo cell array)that converts non-electrical energy (e.g., light) into electricalenergy. The non-electrical energy in this example is light that issupplied to the power supply via a light pipe or fiber optic cable 631and has an energy source that is a light source powered from powersupplied from the LV power line. Such a power supply is disclosed inU.S. application Ser. No. 10/292,745, Attorney Docket No. CRNT-0079,entitled “A Floating Power Supply and Method of Using the Same” filedNov. 12, 2002, which is hereby incorporated by reference.

In still another embodiment of a coupler and isolator shown in FIG. 8,the coupler includes an inductive coupling device having a toroid 602with windings 604 that form part of a coupling transformer. In addition,the coupler includes a power coupling device 680 (e.g., a toroidtransformer) that supplies electrical energy to a power supply 682 topower the electronics on the MV side of the isolator 240

Another example of such a suitable MV coupler is described in U.S.application Ser. No. 10/292,714, Attorney Docket No. CRNT-0110, entitled“A Power Line Coupling Device and Method of Using the Same, ” filed Nov.12, 2002, which is hereby incorporated by reference. This coupler itselfprovides isolation by using the isolation provided by a standardunderground residential distribution MV cable (although it may be usedin an underground or overhead application). Thus, this coupler provideselectrical isolation from the MV voltages while communicating signals toand from the MV power line. Consequently, an embodiment of the presentinvention (in the form of a BD, repeater, backhaul point, or otherdevice) using this coupler may not incorporate a separate isolator 240since the coupler itself provides isolation. In addition, the first MVsignal conditioner 220 also may be omitted or combined with the secondMV signal conditioner 260 when using such a coupler. Such a combinedsignal conditioner may include a MV transmit/receive switch, a filter(e.g., include one or more of band pass, noise, or anti-alias filter) anamplifier, and a frequency translator. Thus, a BD 100 employing thiscoupler may include the functional components shown in FIG. 10.

Path from MV Power Line to LV Power Line

As discussed the MV power line coupler 210 also receives data signalsfrom the MV power line via a coupling device, which may take the form ofany of those coupling devices described above. The data signals from theMV coupler pass through the transient suppression circuitry andimpedance translation circuitry to the MV transmit/receive switch.

Second MV Signal Conditioner

The switch, when in receive mode, passes the incoming data signal to thesecond MV signal conditioner 220, which may provide band pass filteringof the signal (e.g., filtering out signals outside the frequency band ofinterest), amplification of the signal, and additional filtering (e.g.,image rejection filtering, anti-aliasing, noise). The signal is thensupplied to the isolator 240, which in this one embodiment is a fiberoptic cable and transceivers.

Isolator

As discussed, the isolator 240 of the present embodiment providesisolation for both the LV to MV path and the MV to LV path. The input tothe isolator 240 may be conditioned with signal conditioning circuitryassociated with the isolator. Such conditioning circuitry may includecircuitry that filters (e.g., band pass, anti-aliasing, noise),amplifies, and/or performs other processing or conditioning of thesignal.

In this embodiment, the isolator 240 is comprised of a fiber opticisolator including a fiber optic transceiver on the LV side of theisolator and a fiber optic transceiver on the MV side of the isolator.As discussed, the fiber optic transceivers are communicatively coupledthrough a fiber optic conductor(s) or light pipe(s). The isolator 240provides electrical power isolation between the MV power line and the LVpower line, thereby ensuring that the higher voltages of the MV powerline to not reach the LV power line or the customer premises. Inaddition, the isolator 240 ensures that the voltages of the MV powerline do not reach the electronics on the LV side of the isolator, whichare referenced to the neutral of the LV power line. While thisembodiment employs a fiber optic based isolator, other embodiments mayuse an inductive isolator (such as in a transformer), a capacitiveisolator, a wireless path (such as a Bluetooth® wireless path, an 802.11wireless path, an ultrawideband (need more info) wireless path), or somecombination thereof.

As discussed, the isolator 240 may include isolation signal conditioningcircuitry that filters (e.g., band pass, anti-aliasing, noise, etc.),amplifies, and/or performs other processing or conditioning of thesignal. The isolation signal conditioning circuitry may be on the inputor output of the isolator 240 and form part of either communication pathas is necessary.

First MV Signal Conditioner

The output of the isolator 240 is provided to the first MV signalconditioner 260, which may include a low pass filter for filtering outsignals above the uppermost frequency of interest or a band pass filterfor filtering out signals outside the MV communication channel band. Theconditioner 260 of this example embodiment includes a frequencytranslator circuit to shift the frequency of the signal from thefrequencies of the MV communication channel to those of the LVcommunication channel (e.g., 4.5-21 MHz). The second MV signalconditioner 260 may also include an additional filter after thefrequency translation, which may include anti-alias filtering, and/orband pass filtering. In addition, the signal conditioner 260 may includean amplifier for amplifying the signal.

MV Modem

The MV modem 280 receives the output of the first MV signal conditioner260. The MV modem 280 and LV modem 450 provide a bi-directional path andform part of the MV to LV path and the LV to MV path. The components ofthe MV modem 280 have been described above in the context of the LV toMV path and are therefore not repeated here. The incoming signal issupplied to the ADC to convert the incoming analog signal to a digitalsignal. The digital signal is then demodulated. The modem then providesdecryption, source decoding, error decoding, and channel decoding all ofwhich are known in the art and, therefore, not explained in detail here.

The MV modem 280 also provides MAC processing through the use of MACaddresses. In one embodiment employing the present invention, the MACaddress is used to direct data packets to the appropriate device. TheMAC addresses provide a unique identifier for each device on the PLCnetwork including, for example, user devices, BDs, PLIDs, repeaters andbackhaul points (i.e., the LV modems and MV modems of the BDs,repeaters, and the backhaul points).

Based on the destination IP address of a received packet, the backhaulpoint 10 will determine the MAC address of the MV modem 280 of the BD100 servicing the user device. The information for making thisdetermination is stored in a table in the memory of the backhaul point10. The backhaul point 10 will remove the MAC header of the packet andadd a new header that includes the MAC address of the backhaul point 10(as the source address) and the MAC address of the BD 100 (thedestination address)—or more specifically, the MAC address of the MVmodem 280 of the destination BD 100.

Thus, in this embodiment, packets destined for a user device on a LVsubnet of a BD 100 (or to the BD 100) are addressed to the MAC addressof the MV modem 280 of the BD 100 and may include additional information(e.g., the destination IP address of the user device) for routing thepacket to devices on the BD's LV subnet.

If the destination MAC address of the received packet does not match theMAC address of the MV modem 280, the packet may be discarded (ignored).If the destination MAC address of the received packet does match the MACaddress of the MV modem 280, the MAC header is removed from the packetand the packet is supplied to the router 310 for further processing.

There may be a different MAC sublayer for each physical device type suchas for user devices and PLCS network elements (which may include anysubset of devices such as backhaul devices, BDs, repeaters, aggregationpoints, and core routers).

Router

As discussed above, upon reception of a data packet, the MV modem 280 ofa BD 100 will determine if the destination MAC address of the packetmatches the MAC address of the MV modem 280 and, if there is a match,the packet is passed to the router 310. If there is no match, the packetis discarded.

In this embodiment, the router 310 analyzes packets having a destinationIP address to determine the destination of the packet which may be auser device or the BD 100 itself. This analysis includes comparing theinformation in the packet (e.g., a destination IP address) withinformation stored in memory, which may include the IP addresses of theuser devices on the BD 100 LV subnet. If a match is found, the router310 routes the packet through to the LV modem 450 for transmission onthe LV power line. If the destination IP address matches the IP addressof the BD 100, the packet is processed as a command or data intended forthe BD 100 (e.g., by the Command Processing software described below)and may not be passed to the LV modem 450.

The term “router” is sometimes used to refer to a device that routesdata at the IP layer (e.g., using IP addresses). The term “switch” issometimes used to refer to a device that routes at the MAC layer (e.g.,using MAC addresses). Herein, however, the terms “router”, “routing”,“routing functions” and the like are meant to include both routing atthe IP layer and MAC layer. Consequently, the router 310 of the presentinvention may use MAC addresses instead of, or in addition to, IPaddresses to perform routing functions.

For many networks, the MAC address of a network device will be differentfrom the IP address. Transmission Control Protocol (TCP)/IP includes afacility referred to as the Address Resolution Protocol (ARP) thatpermits the creation of a table that maps IP addresses to MAC addresses.The table is sometimes referred to as the ARP cache. Thus, the router310 may use the ARP cache or other information stored in memory todetermine IP addresses based on MAC addresses (and/or vice versa). Inother words, the ARP cache and/or other information may be used withinformation in the data packet (such as the destination IP address) todetermine the routing of a packet (e.g., to determine the MAC address ofthe PLID communicating with the user device having the destination IPaddress).

In an alternate embodiment using IP address to route data packets, allpackets received by the MV modem 280 may be supplied to the router 310.The router 310 may determine whether the packet includes a destinationIP address that corresponds to a device on the BD's LV subnet (e.g., anaddress corresponding to a user device address or the BD's address).Specifically, upon determining the destination IP address of an incomingpacket, the router 310 may compare the identified destination addresswith the addresses of the devices on the subnet, which are stored inmemory. If there is a match between the destination address and the IPaddress of a user device stored in memory, the data is routed to the LVpower line for transmission to the user device. If there is a matchbetween the destination address and the IP address of the BD 100 storedin memory, the data packet is processed as a command or informationdestined for the BD 100.

In addition, the router 310 may also compare the destination addresswith the IP address of the backhaul point 10, other BDs, or otherrepeaters (for example, if the BD is also acting as a repeater). Ifthere is no match between the destination address and an IP addressstored in memory, the packet is discarded (ignored).

According to any of these router embodiments, if the data is addressedto an address on the BD's LV or MV subnet (the network of devices withwhich the BD can communicate and/or for which the BD has an address (MACor IP) stored therein), the router may perform any or all ofprioritization, packet routing, access control, filtering, andencryption.

As discussed, the router 310 of this example embodiment of the presentinvention may use a routing table to determine the destination of a datapacket. Based on information in the routing table and possibly elsewherein memory, the router 310 routes the packets. For example, voice packetsmay be given higher priority than data packets so as to reduce delaysand improve the voice connection experienced by the user. The router 310supplies data packets intended for transmission along the LV power lineto the LV modem 450.

LV Modem

The functional components of the LV Modem 450 have been described abovein the context of the LV to MV path and, therefore, are not repeatedhere. After receiving the data packet from the router 310, the LV modem450 provides MAC processing, which may comprise adding a MAC header thatincludes the source MAC address (which may be the MAC address of the LVmodem 450) and the destination MAC address (which may be the MAC addressof the PLID 50 corresponding to the user device identified by thedestination IP address of the packet).

To determine the MAC address of the PLID 50 that provides communicationsfor the user device identified by the destination IP address of thepacket, the LV modem 450 first determines if the destination IP addressof the packet is an IP address stored in its memory (e.g., stored in itsbridging table). If the IP address is stored in memory, the LV modem 450retrieves the MAC address for communicating with the destination IPaddress (e.g., the MAC address of the PLID 50) from memory, which willalso be stored therein. If the IP address is not stored in memory, theLV modem 450 transmits a request to all the devices to which it iscoupled via the low voltage power line (e.g., all the PLIDs). Therequest is a request for the MAC address for communicating with thedestination IP address of the packet. The device (e.g., the PLID) thathas the MAC address for communicating with the destination IP addresswill respond by providing its MAC address. The LV modem 450 stores thereceived MAC address and the IP address for which the MAC addressprovides communications in its memory (e.g., in its bridging table). TheLV modem 450 then adds the received MAC address as the destination MACaddress for the packet.

The packet is then channel encoded, source encoded, error encoded, andencrypted. The data is then modulated and provided to the DAC to convertthe digital data to an analog signal.

LV Signal Conditioner

The output of the LV modem 450 is provided to the LV signal conditioner420, which conditions the signal for transmission. Knowing (ordetermining) the frequency response (or loss) of the LV power linetransmission channel allows the device to predistort signals prior totransmission to compensate for anticipated losses at certain frequenciesor frequency ranges. During and/or prior to transmission, the amount ofamplification necessary for particular frequency ranges may beperiodically determined according to methods known in the art to providedynamic predistortion (i.e., changing the amount of amplification of allor portions (e.g., frequencies or frequency ranges) of the signal overtime) of the transmitted signal. The determination of the desired amountof amplification may, for example, be determined and/or relate to theamount of amplification performed by amplifiers 422 in the LV to MVpath. Alternately, the amplification may be characteristic for aparticular type of channel (e.g., overhead or underground), or measuredfor a channel, and the predistortion thus may be fixed (preprogrammedand/or hardwired into the device).

In this embodiment, signals at higher frequencies are amplified morethan signals at lower frequencies to compensate for the anticipatedgreater loss at the higher frequencies. As shown in FIG. 6 a, the signalto be transmitted is amplified with an amplifier that provides greateramplification at higher frequencies of the 4.5 to 21 MHz band. Suchamplifiers are well-known to those skilled in the art. The amplifier mayhave a transfer function substantially inverse to the frequency responseof the LV transmission channel. Once amplified and filtered, the signalis conducted through switch 426 to the LV power line coupler 410 fortransmission on the energized LV conductors of the LV power line. Ofcourse, in alternate embodiments the transmission may not bepredistorted and may be filtered and amplified substantially the sameacross the transmission channel.

FIG. 6 b illustrates the transmit circuit used to drive the data signal(indicated by Vs). Components to the left of the dashed line in FIG. 6 bmay be inside the BD enclosure and those to the right may be outside theBD enclosure. The transmit circuit of this embodiment is comprised of atransformer that drives the two conductor pairs 436 and 437. Eachconductor pair 436, 437 is coupled to ground by impedance Z3, which maybe resistive. In addition, each conductor 436 a,b and 437 a,b includes aseries impedance Z1, which may be capacitive (e.g., providing a highpass filter) and/or resistive.

As discussed, the first and second BD cables 436, 437 are each comprisedof a twisted pair of conductors 436 a,b and 437 a,b. As will be evidentto those skilled in the art, each twisted pair cable 436, 437 will havean impedance (determined by the geometry of the cable) as represented byZ2 in FIG. 6 b. This impedance Z2 may be modeled by a resistivecomponent and an inductive component. The inductive component also maycause coupling between the two twisted conductors of each cable.

LV Power Line Coupler

In addition to the above, the LV power line coupler 410 may include theimpedance matching circuitry and transient protection circuitry. Thecoupler 410 couples the data signal onto the LV power line as describedabove for reception by a user device communicatively coupled to the LVpower line via a PLID.

After the LV energized conductors enter the customer premises, typicallyonly one LV energized conductor will be present at each wall socketwhere a PLID might be installed (e.g., plugged in). Given this factregarding the internal customer premises wiring, there is no way to knowto which LV energized conductor the PLID (and user device) will beconnected. In addition, the subscriber may move the PLID and user deviceto another socket to access the PLCS and the new socket may be coupledto the second (different) LV energized conductor. Given these facts, thenetwork designer must supply communications on both LV energizedconductors and, therefore, would be motivated to simultaneously transmitthe PLC RF data signal on each LV energized conductor referenced to theneutral conductor. However, in comparison to transmitting the RF datasignals on both energized conductors referenced to the neutral, thefollowing method of providing communications on the LV energized hasbeen found to provide improved performance.

As shown in FIG. 6 b, the first BD cable 436 is coupled to the LV powerline so that the data signal is applied to the first LV energizedconductor referenced to the LV neutral conductor. The second BD cable437 is coupled to the LV power line so that the data signal (Vs) isapplied to the neutral conductor referenced to the second LV energizedconductor. As a result, the data signal is applied to the first andsecond LV energized conductors differentially. In other words, withreference to the neutral conductor, the voltage signal (representing thedata) on the second LV energized conductor is equal in magnitude andopposite in polarity of the voltage on the first LV energized conductor.Similarly, the current flow representing the data on the second LVenergized conductor will be the opposite of the current flow on thefirst LV energized conductor in magnitude and direction. It has beenfound that differentially driving the LV energized conductors asdescribed provides significant performance improvements over methods,which may result from reduced reflections, improved signal propagation,and impedance matching among other things. It is worth noting thetransmit circuit of this and the following embodiments may transmit datasignals with multiple carriers (e.g., eighty or more) such as with usingan Orthogonal Frequency Division Multiplex (OFDM) modulation scheme.

FIG. 6 c illustrates another embodiment of a transmit circuit fortransmitting the data signal. Components to the left of the dashed linein FIG. 6 c may be inside the BD enclosure and those to the right may beoutside the BD enclosure. The transmit circuit of this embodiment iscomprised of a transformer that drives one conductor pair 436, whichtraverse through a common mode choke. The common mode choke provides avery low impedance to differential currents in the two conductors 436a,b, but provides a significant or high impedance to common modecurrents (i.e., currents traveling in the same direction such as in orout). The two conductors 436 a,b may also be coupled to ground by animpedance Z3, which may be a resistive impedance. In addition, eachconductor 436 a, b includes a series impedance Z1, which may be acapacitive impedance, or other low pass filter component(s), forimpeding the 60 Hz power signal and permitting the RF data signal topass unimpeded. Such impedances may be on either side of the common modechoke, but are preferably on the LV power line side of the choke.

In either embodiment, each conductor may also include a surge protectioncircuit, which in FIG. 6 c are shown as S1 and S2. Finally, the cable436 may be comprised of a twisted pair of conductors between the BDenclosure and LV power line. As will be evident to those skilled in theart, the twisted pair cable 436 may have an impedance (determined by thegeometry of the cable) as represented by Z2. This impedance Z2 may bemodeled by a resistive component and an inductive component. Theinductive component also may cause coupling between the two twistedwired conductors.

While not shown in the figures, the transmit circuit of eitherembodiment may also include a fuse in series with each conductor and avoltage limiting device, such as a pair of oppositely disposed zenerdiodes, coupled between the pair of conductors and may be locatedbetween the common mode choke and the transformer. Finally, one of theconductors of the BD cable(s) 436 or 437 may used to supply power to thepower supply of the BD 100 to power the BD 100.

It is worth noting that these embodiments of the present invention drivethe first and second LV energized conductors differentially to transmitthe data signal (e.g., using OFDM). However, the PLID transmits datasignals from the customer premises to the BD 100 by applying the datasignal to one conductor (e.g., one energized conductor) referenced tothe other conductor such as a ground and/or neutral.

While in this embodiment the two energized conductors are opposite inmagnitude, other embodiments may phase shift the data signal on oneconductor (relative to the data signal on the other conductor) byforty-five degrees, ninety degrees, one hundred twenty degrees, onehundred eighty degrees, or some other value, in addition to or insteadof differentially driving the two conductors.

Controller

A block diagram illustrating most of the functional components of oneembodiment of the present invention is shown in FIG. 9. As discussed,the controller 300 includes the hardware and software for managingcommunications and control of the BD 100. In this embodiment, thecontroller 300 includes an IDT 32334 RISC microprocessor 320 for runningthe embedded application software and also includes flash memory 325 forstoring the boot code, device data and configuration information (serialnumber, MAC addresses, subnet mask, and other information), theapplication software, routing table, and the statistical and measureddata. This memory includes the program code stored therein for operatingthe processor 320 to perform the routing functions described herein.

This embodiment of the controller also includes random access memory(RAM) 326 for running the application software and temporary storage ofdata and data packets. This embodiment of the controller 300 alsoincludes an Analog-to-Digital Converter (ADC) 330 for taking variousmeasurements, which may include measuring the temperature inside the BD100 (through a temperature sensor such as a varistor or thermistor), fortaking power quality measurements, detecting power outages, measuringthe outputs of feedback devices 423, and others. The embodiment alsoincludes a “watchdog” timer 327 for resetting the device should ahardware glitch or software problem prevent proper operation tocontinue.

This embodiment of the controller 300 also includes an Ethernet adapter,an optional on-board MAC and physical (PHY) layer Ethernet chipset 315that can be used for converting peripheral component interconnect (PCI)to Ethernet signals for communicating with the backhaul side of the BD100. Thus, the RJ45 connector may provide a port for a wirelesstransceiver (which may be a 802.11 compliant transceiver) forcommunicating wirelessly to the backhaul point 10 or other BD, which, ofcourse, would include a similar transceiver.

The BD 100 also may have a debug port, such as debug port 317 that canbe used to connect serially to a portable computer. The debug port 317preferably connects to any computer that provides terminal emulation toprint debug information at different verbosity levels and can be used tocontrol the BD 100 in many respects such as sending commands to extractall statistical, fault, and trend data.

In addition to storing a real-time operating system, the memory ofcontroller 300 of the BD 100 also includes various program code sectionssuch as a software upgrade handler, software upgrade processingsoftware, the PLS command processing software (which receives commandsfrom the PLS, and processes the commands, and may return a status backto the PLS), the ADC control software, the power quality monitoringsoftware, the error detection and alarm processing software, the datafiltering software, the traffic monitoring software, the network elementprovisioning software, and a dynamic host configuration protocol (DHCP)Server for auto-provisioning user devices (e.g., user computers) andassociated PLIDs.

Referring to FIG. 9, the router 310 (i.e., processor 320 executing therouting program code) shares a bus with the LV modem 450 and MV modem280. Thus, the router 310 in this embodiment is not physically locatedbetween the two modems, but instead all three devices—the router 310, LVmodem 450, and MV modem 280—are communicatively coupled together via thebus. Consequently, in some instances (e.g., at the occurrence of aparticular event) the router 310 may be programmed to allow the LV modem450 to pass data directly to the MV modem 280 and vice versa, withoutperforming data filtering and/or the other functions performed by therouter 310 which are described above.

This embodiment of the BD 100 may only receive or transmit data over theLV power line at any one instant. Likewise, the BD 100 may only receiveor transmit data over the MV power line at any one instant. However, aswill be evident to those skilled in the art, the BD 100 may transmit orreceive over the LV power line, while simultaneously transmitting orreceiving data over the MV power line.

PLS Command Processing Software

The PLS and BD 100 (or repeater) may communicate with each other throughtwo types of communications: 1) PLS Commands and BD responses, and 2) BDAlerts and Alarms. TCP packets are used to communicate commands andresponses. The commands typically are initiated by the NEM portion ofthe PLS. Responses sent by the BD 100 (or repeater) may be in the formof an acknowledgement (ACK) or negative acknowledgement (NACK), or adata response depending on the type of command received by the BD (orrepeater).

Commands

The PLS may transmit any number of commands to the BD 100 to supportsystem control of BD functionality. As will be evident to those skilledin the art, most of these commands are equally applicable for repeaters.For ease of discussion, however, the description of the commands will bein the context of a BD only. These commands may include alteringconfiguration information, synchronizing the time of the BD 100 withthat of the PLS, controlling measurement intervals (e.g., voltagemeasurements of the ADC 330), requesting measurement or data statistics,requesting the status of user device activations, and requesting resetor other system-level commands. Any or all of these commands may requirea unique response from the BD 100, which is transmitted by the BD 100(or repeater) and received and stored by the PLS.

Alerts

In addition to commands and responses, the BD 100 (or repeater) has theability to send Alerts and Alarms to the PLS (the NEM) via User DatagramProtocol (UDP), which does not require an established connection butalso does not guarantee message delivery.

Alerts typically are either warnings or informational messagestransmitted to the NEM in light of events detected or measured by the BD100. Alarms typically are error conditions detected by the BD 100. Dueto the fact that UDP messages may not be guaranteed to be delivered tothe PLS, the BD 100 may repeat Alarms and/or Alerts that are criticallyimportant to the operation of the device.

One example of an Alarm is an Out-of-Limit Alarm that indicates that anout-of-limit condition and has been detected at the BD 100, which mayindicate a power outage on the LV power line, a temperature measurementinside the BD 100 is too high, and/or other out-of-limit condition.Information of the Out-of-Limit condition, such as the type of condition(e.g., a LV voltage measurement, a BD temperature), the Out-of-Limitthreshold exceeded, the time of detection, the amount (e.g., over,under, etc.) the out of limit threshold has been exceeded, is stored inthe memory of the BD 100 and may be retrieved by the PLS.

Software Upgrade Handler

The Software Upgrade Handler software may be started by the PLS CommandProcessing software in response to a PLS command. Information needed todownload the upgrade, including for example the remote file name and PLSIP address, may be included in the parameters passed to this softwaremodule (or task) from the Software Command Handler.

Upon startup, this task may open a file transfer program such as TrivialFile Transfer Protocol (TFTP) to provide a connection to the PLS andrequest the file. The requested file is then downloaded to the BD 100.For example, the PLS may transmit the upgrade through the Internet,through the backhaul point 10, through the MV power line to the BD wherethe upgrade may be stored in a local RAM buffer and validated (e.g.,error checked) while the BD 100 continues to operate (i.e., continues tocommunicate packets to and from PLIDs and the backhaul point 10).Finally, the task copies the downloaded software into a backup bootpage, and transmits an Alert indicating successful installation to thePLS. A separate command transmitted from the PLS, processed by theCommand Processing software of the BD 100, may make the newly downloadedand validated program code the primary software operating the BD 100. Ifan error occurs, the BD 100 issues an Alert indicating the download wasnot successful.

ADC Scheduler

The ADC Scheduler software, in conjunction with the real-time operatingsystem, creates ADC scheduler tasks to perform ADC sampling according toconfigurable periods for each sample type. Each sample type correspondswith an ADC channel. The ADC Scheduler software creates a schedulingtable in memory with entries for each sampling channel according todefault configurations or commands received from the PLS. The tablecontains timer intervals for the next sample for each ADC channel, whichare monitored by the ADC scheduler.

ADC Measurement Software

The ADC Measurement Software, in conjunction with the real-timeoperating system, creates ADC measurement tasks that are responsible formonitoring and measuring data accessible through the ADC 330. Eachseparate measurable parameter may have an ADC measurement task. Each ADCmeasurement task may have configurable rates for processing, recording,and reporting for example.

An ADC measurement task may wait on a timer (set by the ADC scheduler).When the timer expires the task may retrieve all new ADC samples forthat measurement type from the sample buffer, which may be one or moresamples. The raw samples are converted into a measurement value. Themeasurement is given the timestamp of the last ADC sample used to makethe measurement. The measurement may require further processing. If themeasurement (or processed measurement) exceeds limit values, an alarmcondition may be generated. Out of limit Alarms may be transmitted tothe PLS and repeated at the report rate until the measurement is backwithin limits. An out of limit recovery Alert may be generated (andtransmitted to the PLS) when the out of limit condition is cleared(i.e., the measured value falls back within limit conditions).

The measurements performed by the ADC 330, each of which has acorresponding ADC measurement task, may include BD inside temperature,LV power line voltage, LV power line current (e.g., the voltage across aresistor), AGC1 (corresponding to Feedback device 423 a), and AGC2(corresponding to Feedback device 423 a) for example.

As discussed, the BD 100 includes value limits for most of thesemeasurements stored in memory with which the measured value may becompared. If a measurement is below a lower limit or above an upperlimit (or otherwise out of an acceptable range), the BD may transmit anOut-of-Limit Alarm, which is received and stored by the PLS. In someinstances, one or more measured values are processed to convert themeasured value(s) to a standard or more conventional data value.

The measured data (or measured and processed data) is stored in thememory of the BD. This memory area contains a circular buffer for eachADC measurement and time stamp. The buffers may be read by the PLSCommand Processing software task in response to a request for ameasurement report. The measurement data may be backed up to flashmemory by the flash store task.

The LV power line voltage measurement may be used to provide variousinformation. For example, the measurement may be used to determine apower outage, or measure the power used by a consumer or by all of theconsumers connected to that distribution transformer. In addition, itmay be used to determine the power quality of the LV power line bymeasuring and processing the measured values over time to providefrequency, harmonic content, and other power line qualitycharacteristics.

Traffic Monitoring Software

The Traffic Monitoring software may collect various data packet trafficstatistics, which may be stored in memory including the amount of data(i.e., packets and/or bytes) communicated (i.e., transmitted andreceived) through the MV power line, and/or through the LV power line;the amount of data (packets and/or bytes) communicated (transmitted andreceived) to and/or from the PLS; the number of Alerts and Alarms sentto the PLS; the number of DHCP requests from user devices; the number offailed user device authentications; the number of failed PLSauthentications; and the number of packets and bytes received and/ortransmitted from/to each user device (or PLID 50).

Data Filtering Software

The Data Filtering software provides filtering of data packetstransmitted to and/or from a user device (or PLID 50). The filteringcriteria may be supplied from the PLS (which may be based on requestsreceived from the user) and is stored in memory of the BD 100 and mayform part of the routing table. The Data Filtering software may analyzethe data packets and may prevent the transmission of data packetsthrough the BD:1) that are transmitted to the user device from aparticular source (e.g., from a particular person, user, domain name,email address, or IP or MAC source address); 2) that are transmittedfrom the user device to a particular destination (e.g., to a particularperson, email address, user, domain name, or IP or MAC destinationaddress); 3) that have particular content (e.g., voice data or videodata); 4) based on the time of transmission or reception (e.g., times ofthe day and/or days of the week); 5) that surpass a threshold quantityof data (either transmitted, received, or combination thereof) for apredetermined window of time (e.g., a day, week, month, year, orsubscription period); or 7) some combination thereof.

Auto-Provision and Activation of Network Components

“Auto-Provisioning” is the term used that may be used to refer to thesteps performed to get a new network element (e.g., a BD 100, repeater,or backhaul point 10) onto the PLCS network. While skilled in workingwith power lines, personnel installing the BDs (linemen) often havelittle or no experience in working with communication networks.Consequently, it is desirable to have a system that permits easyinstallation of the BDs without the need to perform networkconfiguration or other network installation procedures.

In the present example embodiment, each network element includes aunique identifier, which may be a serial number. In this embodiment, theenclosure of the BD 100 has a barcode that the installer scans to recordthe serial number. The installer also records the location of theinstalled device. This information (the identifying information andlocation) is provided to a network administrator to input theinformation into the PLS. Alternately, the installer may wirelesslytransmit the information to the PLS for reception and storage by thePLS.

In one example embodiment, after being physically installed and poweredup, the BD transmits a request, such as a dynamic host configurationprotocol (DHCP) request, to the BP 10 with whom the communication deviceis physically or functionally connected. In response to the request, theBP 10 assigns and transmits an IP address to the MV interface 200 (i.e.,assigns an IP address to be used to communicate with the MV modem 280),and the MV subnet mask. In addition, the BP transmits the IP address ofthe BP 10 to be used as the BD's network gateway address, and the IPaddress for the PLS. The BD 100 receives the information from the BP 10and stores it in its non-volatile memory.

The BD 100 then transmits an Alive Alert to the PLS (using the IPaddress received in response to the DHCP request) indicating that the BDis running and connected to the network. The Alive Alert may includeinformation identifying the BD, network configurations of the BD (e.g.,MAC addresses of the LV modem 450 and MV modem 280), the IP address ofthe MV Interface (i.e., the IP address assigned to the MV modem 280received from the BP 10) and MV subnet mask for use by the communicationdevice's backhaul interface (much of which was received from the BP 10).This information is stored by the PLS in the network elements database.

In response, the PLS may activate the BD 100 by assigning andtransmitting the BD 100 a LV subnet mask and a LV Interface IP address(i.e., the IP address used to communicate with the LV modem 450). Ifthere are customers present on the LV subnet, the PLS will transmitcustomer information to the BD 100, which may include such informationas data filtering information, keys (e.g., encryption keys), user deviceIP addresses, and subscription levels for the various users and/or userdevices. In addition, the PLS may configure the BD by transmitting DNSaddresses (e.g., a first and second DNS address), and a registrationserver IP address. This information is stored by the PLS (in the networkelements database) and the BD 100. As discussed below, until a userdevice is registered, the BD 100 may be programmed to allow the userdevice to access only the domain name servers and registration server.

Provisioning a New User Devic

Similarly, when a user installs a new user device on the LV subnetattached to the BD 100, the user device may need to be provisioned toidentify itself on the network. To do so in this embodiment, the newuser device transmits a DHCP request, which is received and routed bythe BD 100 to a DHCP server running in the controller 300 of the BD 100.In response to the request, the BD 100 may respond by transmitting tothe user device the IP address and subnet mask for the user device, thegateway IP address for the device's network interface to be used as thenetwork gateway (e.g., the IP address of the LV modem 450 of the BD100), and the IP addresses of the Domain Name Servers (DNS) all of whichare stored in memory by the user device. In addition, the BD maytransmit a new user device Alert to the PLS.

After provisioning, it may be necessary to register the user device withthe network, which may require providing user information (e.g., name,address, phone number, etc.), payment information (e.g., credit cardinformation or power utility account information), and/or otherinformation to the registration server. The registration server maycorrelate this information with information of the utility company orInternet service provider. The registration server may form part of, orbe separate from, the PLS. Until registered, the BD 100 prevents theuser device (through its PLID 50) from communicating with (receivingdata from or transmitting data to) any computer other than theregistration server or the two DNSs. Thus, until the user device isregistered, the BD 100 may filter data packets transmitted to and/orfrom the user device that are not from or to the registration server ora DNS. In addition, requests (such as HTTP requests) for other Internetweb pages may be redirected and transmitted as a request for theregistration web page on the registration server, which responds bytransmitting the registration web page. Control of access of the userdevice may be performed by limiting access based on the IP address ofthe user device to the IP addresses of the registration server and DNSs.

After registration is successfully completed, the registration servercommunicates with the PLS to provide registration information of theuser device to the PLS. The PLS transmits an activation message for theuser device (or PLID 50) to the BD. In response, the BD 100 removescommunication restrictions and permits the user device (and PLID 50) tocommunicate through the PLCS to all parts of the Internet. As will beevident to those skilled in the art, filtering of data and controllingaccess of the user device may be performed by limiting access based onthe IP address of the user device (or depending on the networkcommunication protocol, the MAC address of the user device) or the MACaddress of the PLID 50 to which the user device is connected. Thus, theBD 100 may compare the source IP address (or MAC address) withinformation in its memory to determine if the IP address (or MACaddress) is an address that has been granted access to the PLCS. If thesource address is not an address that has been granted access to thePLCS (e.g., by registering, which results in an activation message fromthe PLS to the BD 100), the BD 100 may replace the destination IPaddress of the packet with the IP address of the registration server andtransmit the packet to the backhaul point. The procedure above, orportions of the procedure, with respect to provisioning user devices maybe used to provision a PLID instead of or in addition to a user device.

Alternate Embodiments

As discussed, the BD 100 of the above embodiment communicates datasignals to user devices via the LV power line. Rather than communicatingdata signals to the PLID 50 and/or user devices via the LV power line,the BD 100 may use other communication media. For example, the BD mayconvert the data signals to a format for communication via a telephoneline, fiber optic, cable, or coaxial cable line. Such communication maybe implemented in a similar fashion to the communication with LV powerline as would be well known to those skilled in the art.

In addition, the BD may convert the data signal to radio signals forcommunication over a wireless communication link to the user device. Inthis case, user device may be coupled to a radio transceiver forcommunicating through the wireless communication link. The wirelesscommunication link may be a wireless local area network implementing anetwork protocol in accordance with an IEEE 802.11 (e.g., a, b, or g)standard.

Alternatively, the BD 100 may communicate with the user device via afiber optic link. In this alternative embodiment, the BD may convert thedata signals to light signals for communication over the fiber opticlink. In this embodiment, the customer premises may have a fiber opticcable for carrying data signals, rather than using the internal wiringof customer premise.

Backhaul Point

As discussed, the present invention also may be embodied as a backhaulpoint 10. In this alternate embodiment, the device may include acontroller 300, a MV interface 200, and a network interface. Thus, theMV interface of the device would be much the same as that described inthe context of the BD 100 and may include a MV power line coupler 210, afirst MV signal conditioner 220, and a MV modem 280. In addition, some,but not all, embodiments may also include an isolator 240 and/or asecond MV signal conditioner 260 (or the functionality therein).

The controller 300 may include a router 310 coupled to the networkinterface. The network interface may include a network modem, a signalconditioner adapted to condition signals for communication through thenetwork connected to the backhaul point, which may be a wiredconnection. In addition to or instead of a wired connection, thebackhaul point 10 may include a transceiver such as a wirelesstransceiver for communicating with the AP wirelessly (e.g., an 802.11wireless link) or a fiber optic transceiver for communicating with theAP via a fiber optic cable. In addition, the controller 300 of thisembodiment may include substantially the same software and functionalityas that described with respect to the BD 100 and modifications theretowould be readily apparent to one skilled in the art. Specifically, thebackhaul point may include substantially the same functionality withrespect to monitoring data, taking measurements (e.g., temperaturemeasurement), receiving and invoking software upgrades, transmittingdata to the PLS, processing PLS commands (e.g., resets), andtransmitting Alerts and Alarms.

Again, some embodiments of the backhaul point 10, such as those having acoupler with isolation designed in, may not incorporate a separateisolator and all of the signal conditioning circuitry described above.

In an alternate embodiment of the BP 10, the BP 10 is communicativelycoupled to a plurality of MV power lines as shown in FIG. 11. Forexample, the BP 10 may be installed at a location where the MV powerlines intersect in a “T”. This alternate embodiment may include three MVinterfaces with each having its own MV coupler. Each MV coupler 210 maybe communicatively coupled to one of the branches such as branches A, B,and C of FIG. 11. A data filter 901 (such as a high frequency filter orrf choke for attenuating the data signals) is communicatively to the MVphase conductors between each MV coupler 210 to isolate the threecommunication channels of branches A, B, and C. For example, data filter901 c is disposed between MV coupler 210 a and MV coupler 210 b on phase3 of the MV power line. Likewise, data filter 901 f is disposed betweenMV coupler 210 c and MV coupler 210 b on phase 3 of the MV power line.Consequently, data coupled to the MV power line on phase 3 by MV coupler210 b will transmitted through branch B of the MV power line andprevented from traveling down branch A and branch C by data filters 901c and 901 f, respectively.

As discussed above however, the frequency of the data signals may resultin coupling of the data signals from one phase conductor to the other(e.g., from MV phase 3 to MV phase 2 and/or MV phase 1). Consequently,data filters 901 b and 901 e are communicatively coupled to phase 2 ofthe MV power line to prevent signals transmitted by MV coupler 210 b onphase 3 of branch B from coupling to phase 2 (of branch B) and travelingup phase 2 and down branch A or branch C. Likewise, data filters 901 band 901 e prevent signals coupled to phase 2 in branch A and branch C,respectively, from traveling down branch B. Data filters 901 a and 901 dlikewise isolate phase 1 of the MV power line. Typically, the datafilters are installed (i.e., communicatively coupled to block datasignals) at substantially the same longitudinal position on the MV powerline on each of their respective phase conductors as shown in FIG. 11for data filters 901 a-c.

MV coupler 210 b alternatively may be physically installed on a phaseconductor of branch B. In this topology, an additional data filter 910may be installed on each phase conductor of the MV power line betweenthe MV coupler 210 b and the intersection of the three branches A, B,and C.

In yet another alternate embodiment, instead of having a complete andseparate MV interface 200 to couple to each MV phase conductor, the BP10 may have a separate coupler 210, MV signal conditioner(s) and MVisolator 240, but share a common MV modem 280. Preferably, however, theMV isolator 240 forms part of the coupler 210 and does not require aseparate component. In any embodiment, the BP 10 may have two, three,four, or more couplers 210 (and MV interfaces 200) to couple to anydesired number of MV power lines. In addition, in some instances, thedata filters may not be necessary.

In addition and as discussed above, the BP 10 may have a wirelesstransceiver for providing a wireless link to the AP 20 (or distributionpoint as the case may be) and be a wireless BP 10 a. The wireless linkto the AP 20 (or distribution point) may be a direct wireless link ormay include a wireless repeater as shown in FIG. 16. The wirelessrepeater of this embodiment is wirelessly coupled to the AP 20 (ordistribution point), although the communication link could also be awired link or fiber optic link as desired.

In addition, the BP 10, in some instances, may also act as a BD 100serving those consumer premises 40 that receive power from thedistribution transformer 60 to which the BP 10 is coupled. Thus, asshown in FIG. 16, this wireless BP 10 a is a BP in that it acts as abackhaul point to the other BDs 100 a and 100 b that are communicativelycoupled to the MV power line. However, this BP 10 a also is perceived asa BD 100 to the user devices of the LV power lines 61 b to which thewireless BP 10 a is communicatively coupled such as those in consumerpremises 40 c and 40 d. Likewise, a wired BP 10 (that communicatesupstream via fiber, coaxial cable, or via another wired means) also mayservice customers via the LV power lines (or wirelessly). In addition,the wireless repeater may have a wired (or fiber optic) link to the AP20 (or DP) instead of a wireless link as shown in FIG. 16.

Consequently, this wireless BP may be comprised of those componentsshown in FIG. 13 such as a MV interface 200 (including the MV coupler),LV interface 300, and a wireless transceiver. Thus, the wireless BP 10 amay include a router 310 and addressing information stored in memory forcommunicating with the user devices coupled to the MV power line (via aBD 100 and PLID) such as such the MAC addresses of the MV modems oftheir respective BDs 100. In addition, the wireless BP 10 a may havestored in memory the addresses (e.g., PLID MAC addresses) forcommunicating with the user devices coupled to the LV power lines towhich the device 10 a is coupled. In addition, the wireless BP 10 a mayinclude substantially all the functionality of the BD 100 (e.g., forprovisioning user devices, tracking and filtering data, receivingsoftware upgrades, and others described herein) and of the BP 10 (e.g.,sending commands to BDs 100, transmitting software upgrades, and othersdescribed herein).

Repeater

In addition to, or instead of, being used as a transformer bypassdevice, the present invention may also take the form of a repeater.Thus, the repeater 70 may include an MVI interface 200 having many ofthe same components described above such as the MV coupler 210, thefirst MV signal conditioner 220 (which may perform all or some of thefunctions of the first and second MV signal conditioners 220 and 260described above), and the MV modem 280. The repeater may also include acontroller 300 having a router 310. In addition, the device may alsoinclude an isolator 240 and a LV power line coupler 410 (e.g., forcoupling power from the LV line).

In addition, the repeater may include a second MV interface also coupledto the MV line for communicating on the MV power line in a seconddirection—opposite to the direction of communication along the MV fromthat of the first MV interface. Thus, a data filter such as a RF chokemay be disposed on the MV power line between the respective couplingdevices of the couplers of the MV interfaces to prevent datacommunications between the MV interfaces (so that all data is routedthrough the repeater) and so that the MV interfaces do not communicatewith each other over the MV power line (i.e., the two communicationchannels are isolated). Consequently, the repeater may transmit orreceive through the couplers simultaneously. A dual MVI interfacerepeater may be especially suitable for repeating signals throughunderground residential distribution cables. In addition, the repeatermay also include an LVI to also act as a BD (to bypass a distributiontransformer).

In addition to or instead of one of the MV interfaces, and as discussedwith the BD, the repeater 70 may include a wireless transceiver forcommunicating with the backhaul point, a BD, or another repeater.

Depending on the distribution transformer, the allowable radiationlimits, the configuration of the repeater, placement of repeater, andother factors, the repeater may permit communications to be transmittedthrough a distribution transformer for reception by a PLID and/or userdevice coupled to the LV power lines of the transformer and receptiontherefrom. Other embodiments of the repeater may include only one MVinterface and therefore, may only be able to receive or transmit at anyone point in time. Another embodiment of a repeater that providesisolation of networks is described in related U.S. patent applicationSer. No. 10/434,024 (Attorney Docket No. CRNT-0146), entitled “A PowerLine Communication Device and Method of Using the Same,” filed May 8,2003, which is hereby incorporated by reference in its entirety.

Wireless BD

As discussed, the BD 100 is coupled to the low voltage power lines onone side of the distribution transformer and the medium voltage powerline on the other side of the distribution transformer to provide a databypass around the distribution transformer 60. Thus, the BD embodimentdescribed above provides communications for user devices communicativelycoupled to the same low voltage power lines to which the BD is coupledand that extend from the bypassed distribution transformer.Consequently, with the above described BD, a BD 100 may be required foreach distribution transformer to which a user device is electricallycoupled in order to provide communications around the transformer forthose user devices.

In order to reduce the costs of the PLCS, an enhanced BD may be usedalong with a Communication Interface Device (CID) to allow the enhancedBD to provide communication services to additional user deviceselectrically connected to other transformers. In particular, theenhanced BD and CID provide communications for user devices that arecommunicatively coupled to low voltage power lines other than those towhich the enhanced BD is electrically coupled.

An example of such a system employing an enhanced BD (EBD) 500 andmultiple communication interface devices (CIDs) 550 is shown in FIG. 12.FIG. 12 provides just one example of such a system, and is not meant tobe exclusive of all possible systems contemplated by the invention. TheCIDs 550 are communicatively coupled to the EBD 500 via a bi-directionalwireless link and to the user devices at the customer premises 40 viatheir respective low voltage power lines. In this example, a first CID550 a is installed at distribution transformer 60 a and a second CID 550b is installed at distribution transformer 60 c. CID 550 a iscommunicatively coupled to the user devices at customer premises 40 aand 40 b via the low voltage power lines 61 a extending fromdistribution transformer 60 a. Similarly, CID 550 b is communicativelycoupled to the user devices at customer premises 40 e and 40 f via thelow voltage power lines 61 c extending from distribution transformer 60c. EBD 500 is communicatively coupled to the user devices at customerpremises 40 c and 40 d via the low voltage power lines 61 b extendingfrom distribution transformer 60 b. As discussed above, each CID 550 aand 550 b is communicatively coupled to the EBD 500 via a wireless link.Thus, the CIDs 550 provide a means for the EBD 500 to providecommunications for user devices coupled to the low voltages power linesof additional distribution transformers (e.g., distribution transformers60 a and 60 c) and, therefore, provide a means to bypass thoseadditional transformers.

As shown in FIG. 13, the EBD 500 may comprise the same componentsdescribed above for the BD 100 and further include a wirelesstransceiver 316, which may be comprised of an 802.11b wireless modem andan omni-directional antenna. The wireless transceiver 316 may be coupledto Ethernet port 315 of controller 300 (shown in FIG. 9) forcommunication with the router 310.

FIG. 14 is a functional block diagram of a CID, in accordance with oneembodiment of the invention. As shown in FIG. 14, the CID 550 includes aLV interface, (which may be comprised of a LV power line coupler 410 a,a LV signal conditioner 420 a, and a LV modem 450 a) that iscommunicatively coupled to the low voltage power line such as in amanner described above. The CID 550 also may include a power supply thatreceives power from the low voltage power line as described above. TheLV modem 450 a of the LV Interface is coupled to a wireless transceiver510 (e.g., through an Ethernet or MII Interface), which may be comprisedof an 802.11b wireless modem. The wireless transceiver 510 also mayinclude a directional or omni-directional antenna, for example. Thus,CID 550 and the EBD 500 may communicate via a bi-directional wirelesslink via their respective wireless transceivers (510 and 316). Thewireless transceivers may be any suitable wireless transceiver and becomprised, for example, of an 802.11a wireless transceiver, an 802.11bwireless transceiver, or a Bluetooth® transceiver, for example.

Referring to the example embodiment shown in FIG. 12, CID 550 acommunicates with the user devices and PLIDs connected to the lowvoltage power lines 61 a of distribution transformer 60 a such as thoseat customer premises 40 a and 40 b. Similarly, in this one example, CID550 b communicates with the user devices and PLIDs connected to the lowvoltage power lines 61 c of distribution transformer 60 c such as thoseat customer premises 40 e and 40 f. Data from the user devices maytravel through the low voltage power lines (61 a and 61 c) to theirrespective CIDs (550 a and 550 b). The CIDs 550 provide signalconditioning, demodulation, and MAC processing as described above. Inaddition, the CIDs also may transmit the data packets to the EBD 500 viatheir wireless transceivers 510. The EBD 500 then provides routingfunctions as described above, and may forward the data packets to the MVmodem 280 for transmission on the MV power line.

Similarly, data packets intended for user devices communicativelycoupled to the CID 550 (e.g., from the internet via the backhaul point10) may be routed first to the EBD 500. In this particular embodiment,the backhaul point 10 will add the MAC address of the MV modem 280 ofthe EBD 500 as the destination MAC address for data packets withdestination IP addresses for the user devices electrically coupled (vialow voltage power lines) to the EBD 500, CID 550 a, and CID 550 b. Thus,data packets coupled to the MV power line that are intended for userdevices communicatively coupled to the CID 550 may first include the MACaddress of the MV modem 280 of the EBD 500.

Upon determination of a match between the destination MAC address of thepacket and the MAC address of MV modem 280, the MV modem 280 will removethe MAC header and supply the packet to the router 310. The router 310may determine that the destination IP address of the data packetcorresponds to a user device that is communicatively coupled to aparticular CID 550 (e.g., based on the routing table) such as CID 550 aor 550 b. Upon making this determination, the router 310 may retrievethe MAC address of the LV modem 450 a of the CID 550 from memory andinclude it in a MAC header (as the destination MAC address) that isadded to the packet. The router 310 may then route the data packet tothe wireless transceiver 316 to be transmitted to the CID 550 via thewireless link.

The wireless transceiver 510 of the CID 550 receives the data packet andsupplies the data packet to the LV modem 450 a. The LV modem 450 a maycompare the destination MAC address of the packet with the MAC addressof the LV modem 450 a. If the MAC addresses do not match, the packet maybe discarded. If the MAC addresses match, the LV modem 450 a may removethe MAC header and determine the MAC address of the PLID that providescommunications for the user device identified by the destination IPaddress of the packet.

To determine the MAC address of the PLID that provides communicationsfor the user device identified by the destination IP address of thepacket, the LV modem 450 a may first determine if the destination IPaddress of the packet is an IP address stored in its memory (e.g.,stored in its bridging table). If the IP address is stored in memory,the LV modem 450 a retrieves the MAC address for communicating with theIP address (e.g., the MAC address of the PLID) from memory, which willalso be stored therein. If the IP address is not stored in memory, theLV modem 450 a may transmit a request to all the devices to which it iscommunicatively coupled via the low voltage power line. The request is arequest for the MAC address for communicating with the destination IPaddress of the packet. The device (e.g., the PLID) that has the MACaddress for communicating with the destination IP address will respondby providing its MAC address. The LV modem 450 a may then store thereceived MAC address and the IP address to which it providescommunications in its memory (e.g., in its bridging table).

The LV modem 450 a adds a new MAC header (e.g., that includes the MACaddress of the PLID that provides communication for the user deviceidentified by the destination IP address of the packet) to the packetand transmits the packet through the low voltage power line via coupler410 a. As will be evident to those skilled in the art, the CID 550, andin particular the LV modem 450 a of the CID 550, includes routinginformation (e.g., a routing table and rules) stored in memory therein,which may include the MAC addresses (e.g., for PLIDs) and/or IPaddresses (e.g., for the user devices) of devices communicativelycoupled to the subnet of the CID 550.

The packet is then received by the PLID, which supplies the data packetto the appropriate user device and which may or may not remove the MACheader prior thereto.

Thus, in this particular embodiment, a single EBD 500 may providecommunications through one or more CIDs 550 to user devices that arecoupled to low voltage power lines other than the low voltage powerlines to which the EBD 500 is physically coupled. The EBD 500 mayprovide communications through one, two, three, four or more CIDs 550,thereby providing communications for up to fifty or more users (e.g.,eight CIDs 550 with eight user devices each and eight user devicescoupled to the low voltage power lines that are coupled to the EBD 500).

In the above example, the CIDs 550 are coupled to low voltage powerlines that receive power from the MV power line that is the same as theMV power line to which the EBD 500 is coupled (via coupler 210).However, the CIDs 550 may be coupled to LV power lines that receivepower from a MV power line that is different from the MV power line towhich the EBD 500 is coupled. In other words, one or more CID 550 may becoupled to LV power lines that receive power from a first phase andsecond phase of the MV power line conductors and the EBD 500 may becoupled to a third phase of the MV power line conductors. In addition, aCID 550 may be coupled to LV power lines that do not receive power fromthe same set of three phase MV power lines (i.e., the LV power lines mayreceive power from a different set of three phase MV power lineconductors).

A CID 550 may be mounted adjacent a distribution transformer (andcoupled to the LV power lines thereof on each side of the EBD 500 asshown in FIG. 12. Furthermore, additional CIDs 550 may be installedfurther down or up the MV power line. In other words, one or more CIDs550 may be installed on either or both sides of the EBD 500 so thatthere are two or more CIDs 550 on one or both sides of the EBD 500 alongthe MV power line. Also, a CID 550 need not be installed at thetransformer adjacent the EBD 500. All that is required for operation forthis embodiment is that the CIDs 550 be communicatively coupled to auser device and to the EBD 500. Depending on the wireless transceiversused, as well as other environmental considerations, the system mayrequire a clear line of sight between the antenna of the EBD 500 and theantennas of the CIDs 550.

Other embodiments of the CID 550 may include a controller (whichincludes a processor, additional memory (e.g., RAM, ROM, PROM, and/orEPROM), and program code). In this alternate embodiment, the CID 550 maybe assigned (and store in memory) an IP address to allow the PLS totransmit commands to the CID 550 and collect data therefrom. Inaddition, this alternate embodiment may assign IP addresses to userdevices and may include a router and provide routing functions asdescribed above with respect to the BD 100 (e.g., such as prioritizingvoice packets over data packets or prioritizing based on the user deviceoriginally transmitting the packet).

Alternately, the CID 550 may be designed to perform minimal or no anypacket processing. In other words, the CID 550 may simply receive apacket from the LV power line and wirelessly transmit the packet to theEBD 500 (or other wireless device). Similarly, the CID may receivepackets wirelessly and transmit those packets (substantially in tactwithout, for example, modifying the MAC header) on the LV power line. Inthis embodiment, the EBD 500 (or other wireless capable device) wouldinclude the bridge tables and add the MAC address of the PLIDcorresponding to the user device addressed by the IP packet. Likewise,the PLIDs may store the MAC address of the EBD 500 wirelessly coupled tothe CID 550. Thus, the CID 550 may be designed to perform varying levelsof packet processing such as minimal packet processing (transmit allpackets), perform MAC address processing, or perform IP (and MAC)address processing.

In addition, in the above embodiment the EBD 500 provides communicationsto the user devices coupled to the low voltage power lines to which itis coupled via coupler 210. However, in some instances that employ analternate embodiment of the EBD 500, it may not be desirable to providecommunications through the low voltage power lines. Thus, the alternateembodiment of the EBD 500 may not require most of a LV interface and maycouple to the LV power lines only to draw power therefrom (i.e., notcommunicate data therethrough).

In still another embodiment, the CID 550 does not communicate to theuser devices via the low voltage power lines, but instead communicateswith the user devices and/or another CID 550 via a wireless link. Inthis alternate embodiment, the CID 550 may use the same wirelesstransceiver (e.g., with an omni-directional antenna) to communicate withthe user devices and/or CID 550 (e.g., via an 802.11 wireless accesspoint at the customer premises) and with the EBD 500. In still anotherembodiment, the CID 550 may use a first wireless transceiver (e.g., withan omni-directional antenna) to communicate with the user devices (e.g.,via an 802.11 wireless access point at the customer premises) and asecond wireless transceiver to communicate with the EBD 550. Eachtransceiver may be communicatively coupled to a controller (in the CID550) that may perform routing functions and PLS communications asdescribed above.

As an alternate to this embodiment, the CID 550 may be configured tosimply shift the frequency of the wireless signal (such as a digitalspread spectrum (DSS) signal or 802.11 signal) it receives from the EBD500 and couple the signal to the LV power line for transmission throughthe LV power line and reception by a user device or other intermediatedevice designed to receive and process such signals. Likewise, the EBD500 may be configured to simply frequency shift the received wirelesssignals (such as a DSS or 802.11 signal) and transmit them through theMV power line for reception by a backhaul point designed to receive andprocess such signals.

Transmission from the backhaul point through the MV power line (and fromthe user device through the LV power line) may be of the sametransmission type (e.g., a DSS or 802.11 frequency shifted signal) ormay be of another transmission type.

In many neighborhoods and geographical areas, the customer premisesreceive electrical power via underground power lines. For example, a padmounted or underground transformer receiving receive power via anunderground MV power line, may supply power to one or more user premisesvia underground LV power lines. In some instances, the pad mounted orunderground transformers may be in an enclosure that may be difficult toaccess for installing PLC devices. In other instances, it simply may bemore desirable to provide power line communications to the userpremises—whether the electrical distribution network of the geographicalarea includes underground and/or overhead power lines—without employingthe MV power lines and/or a MV interface 200.

Thus, another embodiment of a communication device of the presentinvention utilizes existing electrical distribution networkinfrastructure as an insertion point (a location on the electricaldistribution network for inserting and/or extracting data signals) forthe PLCS.

In one example embodiment shown schematically in FIG. 15, a street light62, such as those receiving power from a LV power line, may provide aninsertion point for the PLCS. The street light 62 may be on the same LVsubnet as one or more customer premises. In other words, the LV powerline providing power to the street light 62 may also be electricallycoupled to one or more customer premises 40 as shown. This electricalconnection—between the street light 62 and the customer premises 40—maythus be used to provide power line communications. Thus, the CID 550need not be installed at a distribution transformer and may becommunicatively coupled to existing electrical distribution networkinfrastructure to provide communications to the user devicescommunicatively coupled to the LV subnet to which the electricaldistribution network infrastructure is coupled.

Street lights, such as those mounted to street light poles, are oneexample of existing electrical distribution network infrastructure thatmay be used as an insertion point. Street lights often have a photocellmounted on the top side of the light fixture. Based on the ambient lightdetected, the photocell controls whether the street light is turned onor off. The photocell includes a plug that plugs into a socket on thetop of the light fixture. Thus, the photocell receives power from thesame source as the street light itself, which typically is the LV powerline. In the United States, both energized conductors typically are usedto power the street light, thereby providing access to both LVconductors for communications.

In this example, the LV power line coupler 410 a of this embodiment ofthe CID 550 includes a cylinder shaped device that includes a plug onone side and a socket on the other side. The plug is adapted to pluginto the socket on top of the street light fixture. The socket of thecoupler 410 a is adapted to receive the plug of the photocell. Thecoupler 410 a allows the photocell to receive power from the streetlight, but also provides a method of communicatively coupling the CID550 to the LV power line (e.g., both energized conductors and theneutral) to provide communications to the user devices on the LV subnet.In addition, the CID 550 also preferably includes a power supply thatreceives power from the LV power line via the coupler 410 a as describedabove.

While in this example embodiment the CID 550 is communicatively coupledto a street light, other electrical distribution network infrastructureto which the CID may be coupled include a traffic light (or LV powerlines or control box coupled to the traffic lights), a hazard light, asign (e.g., a business sign), decorative lighting, a billboard, or otherelectrical infrastructure. In addition, the CID 550 may becommunicatively coupled to the LV power line at a customer premises 40(e.g., outside such as on top of the premises or at an outdoorelectrical outlet). For example, the antenna of the CID 550 may beinstalled on top of the premises (e.g., on or near the roof) while theremaining portion of the CID 550 may be mounted indoors (e.g., in theattic). The LV coupler 410 a may be comprised of a wall socket plug thatplugs into a wall socket, such as a 120V wall socket (or alternatively a240V socket), or be designed to mate with a light bulb socket. Thus,these embodiments of the coupler 410 a include a male portion adapted tomate with a female receptacle. The male portion of the coupler 410 a isin electrical communication with a female receptacle of the coupler 410a, which is adapted to receive the male projection of an electricaldevice. The male portion and female receptacle of the coupler 410, maybe electrically coupled together by one or more conductors (depending onhow many conductors are present in the external female receptacle withwhich the coupler is designed to be used). In addition, the male portionof the coupler 410 a, the female receptacle of the coupler 410 a, orboth are communicatively coupled to a transceiver (e.g., a modem) suchas through signal conditioning circuitry (as discussed above) and mayalso supply power to a power supply.

If the LV coupler 410 a is coupled only to one LV energized conductor(e.g., in the case of a light socket or 120V wall socket), a LV datasignal coupler may be installed (e.g., elsewhere in the premises) tocouple the data signals from the first LV energized conductor to thesecond LV energized conductor. Such LV data signal couplers arewell-known in the art. Depending on the geometry of the energizedconductors and the strength and frequency of the data signals, a LV datasignal coupler may not be necessary.

While the electrical distribution network infrastructures describedabove use (consume) electricity (e.g., to illuminate the light in thestreet light, to illuminate the billboard, to control and/or illuminatethe traffic light), other electrical distribution networkinfrastructures may not themselves use electricity, but may simply houseor be physically near the LV power lines.

Ideal structures for installation of a CID 550 as an electricaldistribution network infrastructure insertion point are those thatinclude a portion with a higher elevation than surrounding structures(e.g., buildings, trees, etc.) and have a LV power line (preferably withtwo low voltage energized conductors). However, the CID 550 may beinstalled anywhere communications can be achieved.

The CID 550 may be designed and installed to communicate with anywireless device that facilitates communications—hereinafter referred toas a CID Link. As discussed, it may be configured (designed andinstalled) to communicate with a CID Link that is an EBD 500. However,the CID 550 also may be configured to communicate with other CIDs 550.In addition, the CID 550 may be configured to communicate with awireless repeater—which repeats the data to and from a backhaul point 10(or AP 20) configured with a wireless transceiver. Similarly, the CID550 may be configured to communicate with a device (e.g., an AP 20,distribution point, BP 10) that includes a wireless transceiver (andprovides communications for a plurality of CIDs 550) and a linetransceiver such as fiber optic transceiver or wired conductortransceiver (e.g., a conventional copper wire modem) for providingcommunications to and from the Internet or other destination.

In addition, a plurality of wireless repeaters (which may act as a BP10) each may be configured to provide wireless communications with aplurality of CIDs 550. Each wireless repeater may be configured tocommunicate data (upstream) with an AP 20 (or distribution point) viawireless or wired link.

Thus, the CID Link may take the form of an EBD 500, a wireless repeater,a backhaul point with a wireless transceiver, an AP 20 having a wirelesstransceiver, another CID 550, or another device with wirelesscapabilities. Thus, one CID 550 may provide communications for, and actas a backhaul point 10 for, other CIDs 550 in much the same way asdescribed for the wireless BP 10 a above. Consequently, a plurality ofCIDs 550 may form a wireless network in much the same way a wirednetwork is formed by the BDs 100 and BP 10 described above.

The CID Link, whichever embodiment it takes, may be installed at anysuitable location such as on a water tower, a mobile telephonecommunications tower, a radio tower, a television broadcast tower, atelephone pole, an electric utility pole, a street light, a hill top, abuilding, a traffic light, a billboard, a sign, decorative light, orother suitable structure. In one embodiment, a plurality of CIDs areinstalled on a plurality of utility poles for coupling to the LV powerlines. The CIDs 550 are wirelessly linked to a CID Link that provides BPfunctionality and which is communicatively coupled to an AP 20.

As discussed, the CID 550 may be designed to perform varying levels ofpacket processing such as minimal packet processing (transmittingsubstantially all packets), perform MAC address processing, or performIP (and MAC) address processing (and therefore, may or may not include arouter).

Depending on the design of the network (and CID), each of the pluralityof CIDs 550 in the network may have a unique MAC address, have a uniqueMAC address and IP address (e.g., an IP address assigned by the PLS asdescribed above), or may simply pass through all packets without regardto addresses. The PLS may assign IP addresses to (if applicable), andstore the location and other configuration information (serial number,address(es), subnet mask, and other information) of, each CID 550 (andCID Link if applicable) as described above with respect to the BD 100.

The communication network may thus be comprised of a plurality of CIDLinks (communicatively coupled to one or more AP 20) that each providescommunications for a plurality of CIDs 550, which each providescommunications to the user devices of one or more customer premises (viathe LV power lines and/or wirelessly). The communication network mayalso include the MV attached network elements previously described(which may include a unique MAC and/or IP address) such as numerouswireless BPs 10 a, backhaul points 10 (which may be communicativelycoupled to one or more AP 20, which may be the same or different AP 20to which the CID Links are coupled), which are coupled to BDs 100,repeaters 70, EBD 500, and other MV power line attached devices. Asdiscussed, the configuration information and other information of eachnetwork element (MV coupled and wireless devices) may be stored in thePLS.

As will evident to those skilled in the art, the LV interface may becomprised of a signal conditioner (if any), a coupler, and thetransceiver (i.e., transmitter and receiver), which may be a modem. TheLV interface 400 may be combined with a wireless transceiver (asdiscussed in the context of CID 550) and/or a MV interface 200 (asdiscussed in the context of BD 100). In addition, the LV interface 40may be combined with another LV interface 400 to couple data signals,for example, to another LV power line (e.g., another LV subnet, whichmay have two separate LV energized conductors). Any of thesecombinations may also include a controller (which may or may not haverouter functionality) as described above.

Topology

It will be evident to those skilled in the art that the PLC devicesdescribed herein permit a great deal of flexibility in network topology.One example topology is shown in FIG. 17 a, which includes a first group(Group A) and second group (Group B) of PLC devices. Group A iscomprised of a BP 10 in communication with AP 20. The communication linkbetween the BP 10 and the AP 20 may be wireless, wired, fiber optic, oranother type of link. Group A is also comprised of four bypass devices100 and one repeater 70 a. The repeater 70 a of this embodiment is aMV-wireless repeater that is communicatively coupled to the MV powerline and that repeats data through the MV power line or wirelessly. Therepeater 70 a thus includes a MV interface 200 (as described herein), acontroller 300 (which may include a router), and a wireless transceiver316 (as described herein in the context of the CIDs 550 and EBDs 500).

Group B is comprised of a wireless BP 10 a that acts a first backhaulpoint for the five BDs 100 in Group B. In other words, the wireless BP10 a is in communication with the BDs 100 in Group B via the MV powerline. In addition and as discussed, a wireless BP 10 a includes awireless transceiver for wireless communications, and in thisembodiment, the wireless BP 10 a is configured for wirelesscommunications with the repeater 70 a of Group A.

Due to noise, attenuation, and other characteristics of power lines, aBP (such as the BP 10 of Group A) will be able to reliably communicatedata only a finite distance. In this example, the BP 10 may directlycommunicate with the repeater 70 a, but not with the wireless BP 10 a.However, the BP 10 may provide communications for Group B via thewireless link between the repeater 70 a and the wireless BP 10 a. Morespecifically, data transmitted on the MV power line by a BD 100 in GroupB is received by the wireless BP 10 a and wirelessly transmitted. Therepeater 70 a receives the wirelessly transmitted data, may process thedata, and transmits the data on the MV power line. The BP 10 receivesthe data via the MV power line and processes the data as describedherein (e.g., MAC processing and transmission to the AP 20 fortransmission on a network such as the Internet).

Data from the AP 20 intended for a user device serviced by a PLC devicein Group B will be received by the BP 10. Based on the destination IPaddress of the data packets and information in the routing (or bridge)table, the BP 10 may insert the MAC address of the MV modem of therepeater 70 a as the destination MAC address. The data packets are thenreceived by the repeater 70 a. Based on the destination IP address ofthe data packets and information in the routing (or bridge) table of therepeater 70 a, the repeater 70 a may insert the MAC address of the MVmodem of the PLC device in Group B that services the user device(corresponding to the destination IP address) as the destination MACaddress of the packet. Thus, the wireless BP 10 a may receive the data,and transmit all data on the MV power line that is not addressed to theBP 10 a. Alternately, the repeater 70 a may transmit all the data andthe wireless BP 10 a may insert the MAC address of the MV modem of thePLC device in Group B that services the user device (corresponding tothe destination IP address) as the destination MAC address of thepacket. The repeater 70 a or wireless BP 10 a (as the case may be) mayignore packets with IP addresses (and/or MAC addresses) that do notcorrespond to a user device serviced by a PLC device in Group B. Oncethe data packet is received by the correct PLC device in Group B, thepacket is processed as described above (e.g., signal processing, MACprocessing, etc.).

Thus, the wireless link between the repeater 70 a and the wireless BP 10a permits communications over a portion of the power lines that mightnot otherwise be obtainable by the BP 10 alone. While in this exampleembodiment Group B is on the same power line as Group A, some or all ofthe devices of Group B may be communicatively coupled to a differentphase conductor or on a conductor in a different conductor set (e.g., adifferent three phase conductor set). While in this embodiment therepeater 70 a is used to establish the wireless link, another embodimentinstead may use an EBD 500 in Group A, which additionally services itsown customer premises (e.g., via the LV power lines or wirelessly), toestablish the wireless link. Likewise, while the above embodiment uses awireless BP 10 a in Group B to establish the wireless link, anotherembodiment may use a MV-wireless repeater 70 a (which may have a MVinterface, controller, and wireless transceiver) in Group B, which maynot service any customer premises and/or perform backhaul functions.

The groups of the above example are disposed so that the communicationson the MV power line of either group may not be received by the PLCdevices of the other group, thereby providing network isolation betweenthe groups. This network isolation may be caused by the attenuation ofthe data signals traveling from one group toward the other, which may bedue to the distance between the groups along the power line, the factthat the groups are on different conductors or different sets ofconductors, and/or the use of one or more attenuators (e.g., RF chokes)between the groups. In addition, the network isolation may be providedthrough the use of software methods to isolate the groups (e.g., usingdifferent addressing, using different encryption keys, or usingdifferent carrier frequencies for each group).

While the above embodiment employs a wireless link between Group A andB, other embodiments may use a fiber optic link, a twisted conductorpair link, a coaxial cable, or another type of communication link. Oneadvantage of these non-power line links is that the BDs 100 in thegroups cannot receive the wireless, fiber optic, coaxial, or twistedpair communications as the case may be, and therefore, cannot getconfused by receiving data not intended for the BDs 100. In other words,the non-power links facilitate communication between the desired PLCdevice of each group, but otherwise maintain the isolation between thegroups. However, other embodiments may use the MV power line conductoras the communication link. In such an embodiment, another method (e.g.,using different addressing, using different encryption keys, or usingdifferent carrier frequencies for each group) may be used to isolatecommunications of the groups of BDs 100. While the above embodimentsinclude the BDs 100 in the groups, the groups also (or instead) mayinclude CIDs 550, additional MV repeaters, EBDs 500, other PLC devices,or some combination thereof. In addition, one or more additional groupsmay be added that are comprised of the components of Group B and therebyare communicatively linked to Group A via repeater 70 a (or anadditional repeater 70 a designated for communication with theadditional group) or to an alternative wireless BP 10 a in Group A.Finally, another group could added (e.g., having the components of GroupB) to communicate with Group A via Group B, which may further include arepeater 70 a.

In another example topology, the PLCS may be comprised of a plurality ofgroups of CIDs 550 that each provide communications to one or morecustomer premises (e.g., via the LV power lines). In this example, eachCID 550 is in communication (wirelessly) with either a BP 10 withwireless capabilities (that is in communication with an AP 20), awireless repeater such that shown in FIG. 16 that is wirelessly linkedto an AP (perhaps through a BP 10), or an AP 20 that includes wirelesscapabilities. Thus, in some embodiments of this topology there may be noneed for a backhaul point or communications over the MV power line.

As is known in the art, each PLC device coupled to the power lineconductor may have a “through loss” and a “coupling loss.” The throughloss is the reduction in the strength (power) of the data signals asthey pass through the PLC device (e.g., the coupling device of the PLCdevice) while traversing the power line conductor. For example, thethrough loss of a PLC device (e.g., a BD 100) reduces the power of thedata signals transmitted by a BP 10 that traverse through the PLC deviceand are received by a second PLC device (such as a BD 100, repeater 70,etc.) further down the power line. Likewise, the through loss may bebi-directional and, therefore, may reduce the power of the data signalstransmitted by the second PLC device (e.g., a BD 100, repeater 70, etc.)further down the power line that traverses up the power line, throughthe PLC device to the BP 10. Thus, the through loss of devices on apower conductor reduces the distance over which the data signals canreliably communicated over that power line conductor.

Coupling loss is the power loss of the data signals as that are coupledoff of (or onto) the power line conductor (e.g., to or from theelectronics of the PLC device). In other words, when the data signalsarrive at the PLC device (e.g., its coupler) on the power line, the datasignals must have power that is equal to or greater than the couplingloss of the PLC device for the data signals to be reliably received bythe PLC device.

For example, assume that the through loss of each BD 100 in Group A isten decibels (dB) and the coupling loss of the repeater 70 a is fifteendB. If the data signals transmitted by the BP 10 in FIG. 17 a are fortydB above the noise (i.e., the link budget is forty dB) when coupled ontothe MV power line conductor, the data signal will essentially beindiscernible from noise after traversing through four BDs 100. This isbecause the combined power loss due to the through loss of the four BDs100 will be equal to the forty dB of power supplied by the BP 10.However, if the data signals are transmitted by the BP 10 at sixty dBabove the noise, the data signals will be received by the repeater 70 a,because forty dB will be the loss due to the BDs 100 and fifteen dB willbe the loss due to the coupling loss of the repeater 70 a leaving fivedB of excess power. These examples are for illustrative purposes, ofcourse, and assume that the power line itself is lossless, which is nota valid assumption in real world applications.

FIG. 17 b illustrates a method of arranging PLC devices to minimize theeffects of the PLC devices' through loss on the PLCS performance. Asdiscussed, the data signals may be transmitted using modulationtechniques that use carrier frequencies in the megahertz range. Due tothese frequency ranges and the physical arrangement of the power lines(e.g., their diameter and spacing), the data signals may couple from onephase conductor to one or more of the other phase conductors, whichtypically run in parallel.

As shown in FIG. 17 b, the BP 10 is communicatively coupled to themiddle conductor (Phase B) of the three MV power line conductors. Inthis embodiment, the BP 10 provides communications to all of the BDs 100in FIG. 17 b. The BP 10 communicates with the BDs 100 b coupled to PhaseB via the Phase B power line conductor. The BP 10 communicates with theBDs 100 a coupled to Phase A via coupling of the data signals from thePhase B conductor to the Phase A conductor. The BP 10 communicates withthe BDs 100 c coupled to Phase C via coupling of the data signals fromthe Phase B conductor to the Phase C conductor. The BDs 100 c on Phase Cand BDs 100 a on Phase A may provide communications for customerpremises between the BP 10 and BDs 100 b. However, the BDs 100 c and 100a are not communicatively coupled to Phase B and, therefore, cause asignificantly less (or substantially zero) through loss to the datasignals communicated to the BDs 100 b on Phase B. It is worth noting,however, that the BDs 100 c on Phase C and BDs 100 a on Phase A may havea greater effective coupling loss than they would if coupled to Phase Bbecause there will be a loss as the data signals couple from Phase B toeither Phase A or C.

In addition, the data signals may couple from Phase B to Phase A forreception by the BD 100 a 1, thereby circumventing at least a portion ofthe through loss of the BDs 100 a that are between the BP 10 and BD 100a 1. It will be evident from the description herein that a PLC device,such as a transformer bypass device 100, a BP 10, and an EBD 500, may becoupled to any MV power line phase desired by the network designer.Specifically, the PLC devices do not need to be (although they may be)coupled to the MV power line phase conductor that supplies power to thedistribution transformer electrically coupled to the LV power line(s) towhich the PLC device is coupled. For example, referring to FIG. 17 b,the BDs 100 b shown on phase B may service customer premises that aresupplied power by a transformer coupled to (and receiving power from)Phase A or C.

As will evident to those skilled in the art, the topology of FIG. 17 b(and principles taught therein) could be used for (or in) the topologyof Group A and/or B in FIG. 17 a (and with the principles taughttherein).

Miscellaneous

As discussed, the functions of the PLID may be integrated into a smartutility meter such as a gas meter, electric meter, or water meter. Themeter may be assigned an IP address by the PLCS (e.g., by the PLS) and,upon receiving a request or at predetermined intervals, transmit datasuch as consumption data to the BD 100, the PLS, and/or a utilitycomputer system in a manner described herein, thereby eliminating theneed to have utility personnel physically travel to read the meter. Inaddition, one or more addressable switches, which may form part of autility meter, may be controlled via the PLCS (e.g., with commandstransmitted from the BD 100, the PLS, and/or utility computer system) topermit connection and disconnection of gas, electricity, and/or water tothe customer premises.

Similarly, the PLCS may be used to control MV power line switches. Theaddressable MV power line switch may be a motorized switch and assignedan IP address by the PLS, which is also provided to the utility computersystem to thereby operate the switch. When a power outage is detected,the utility company may remotely operate one or more addressable MVpower line switches to provide power to the area where the outage isdetected by transmitting commands to the IP addresses of the switches.

Likewise, the PLCS may be used to operate a capacitor switch thatinserts or removes a capacitor (or capacitor bank) into the powerdistribution system. Capacitor banks are used to improve the efficiencyof the power distribution network by providing Volt/VAr management(e.g., modifying the reactance of the power distribution network). Thus,the PLS may assign an IP address to one or more capacitor switches,which is also provided to the utility computer system to thereby operatethe switch. Based on power quality measurements taken and received fromone or more BDs, the utility company may insert or remove one or morecapacitor banks by remotely actuating one or more capacitor bankswitches by transmitting commands to the IP addresses of the switches.

The capacitor switch and the MV power line switch may be controlled byan embodiment of the present invention that includes a MV interface andcontroller. In addition, in some embodiments a LV interface may also beemployed.

The PLID 50 in the above embodiments has been described as a device thatis separate from the user device. However, the PLID 50 may also beintegrated into and form part of the user device.

While the above described embodiments utilize a single modem in the LVinterface and the in the MV interface, alternate embodiments may use twomodems in the LV interface and two modems in the MV interface. Forexample, the LV interface may comprise a receive path (for receivingdata from the LV power lines) that includes a LV modem and signalconditioning circuitry and a transmit path (for transmitting datathrough the LV power lines) that includes a second LV modem and signalconditioning circuitry. Each LV modem may have a separate address (MACand IP address) and operate at a separate frequency band. Thus, thereceive or transmit LV interfaces may also include frequency translationcircuitry.

Likewise, as another example the MV interface may comprise a receivepath (for receiving data from the MV power line) that includes a MVmodem and signal conditioning circuitry and a transmit path (fortransmitting data through the MV power line) that includes a second MVmodem and associated signal conditioning circuitry. Each MV modem mayhave a separate address (MAC and IP address) and operate at a separatefrequency band. Thus, the receive or transmit MV interfaces may alsoinclude frequency translation circuitry. A repeater may also beconstructed with multiple MV modems in both of its MV interfaces or inits only MV interface as the case may be.

While the described embodiments may apply the data signals to one MVconductor (and the data signals may couple to other conductors), otherembodiments may apply the data signals differently. For example, a firstMV coupler (and an associated MV interface) may be coupled to a first MVconductor for transmitting data on the MV conductor and a second MVcoupler may be coupled to a second MV conductor for receiving the returncurrent of the transmitted data. The two couplers may thus share asignal MV modem. Similarly, the first and second couplers (coupled tothe first and second MV power line conductors) may transmit (andreceive) the data signals differentially as described above in thecontext of the LV power line transmissions and shown in FIGS. 6 b and 6c. Thus, the same data signal may be transmitted down multiple MVconductors with the signal on each conductor being phase shifted (e.g.,120 degrees or 180 degrees) with respect to the signal(s) on the otherconductor(s). Alternately, in any of these embodiments, the neutralconductor may be used (e.g., as a return path or separate transmissionpath) instead of one or more of the MV conductors.

As will be evident to those skilled in the art, the backhaul points andPLIDs for communicating with these alternate embodiments of the bypassdevice (or repeater) would also require similar circuitry fortransmitting and receiving with multiple modems and in the differentfrequency bands. More specifically, the modified backhaul point and/orPLID would also require a first and second modem for transmitting andreceiving, respectively, and designed to operate in the appropriatefrequency bands for establishing communications. Such a system wouldpermit full duplex communications through the power lines.

In the above embodiment, the processor performs routing functions andmay act as a router in some instances and perform other functions atother times depending on the software that is presently being executed.The router may also be a chip, chip set, or circuit board (e.g., such asan off the shelf circuit card) specifically designed for routing, any ofwhich may include memory for storing, for example, routing information(e.g., the routing table) including MAC addresses, IP addresses, andaddress rules.

The isolator described above provides a non-electrical signal path(i.e., for transmission of a signal that is non-electrical), which is afiber optic signal path. However, any non-electrical signal may be usedsuch as a radio frequency signal, a microwave signal, and the like.

Finally, the type of data signal coupled by the coupling device may beany suitable type of data signal. The type of signal modulation used canbe any suitable signal modulation used in communications (Code DivisionMultiple Access (CDMA), Time Division Multiple Access (TDMA), FrequencyDivision Multiplex (FDM), Orthogonal Frequency Division Multiplex(OFDM), and the like). OFDM may be used one or both of the LV and MVpower lines. A modulation scheme producing a wideband signal such asCDMA that is relatively flat in the spectral domain may be used toreduce radiated interference to other systems while still deliveringhigh data communication rates.

It is to be understood that the foregoing illustrative embodiments havebeen provided merely for the purpose of explanation and are in no way tobe construed as limiting of the invention. Words used herein are wordsof description and illustration, rather than words of limitation. Inaddition, the advantages and objectives described herein may not berealized by each and every embodiment practicing the present invention.Further, although the invention has been described herein with referenceto particular structure, materials and/or embodiments, the invention isnot intended to be limited to the particulars disclosed herein. Rather,the invention extends to all functionally equivalent structures, methodsand uses, such as are within the scope of the appended

Those skilled in the art, having the benefit of the teachings of thisspecification, may affect numerous modifications thereto and changes maybe made without departing from the scope and spirit of the invention.

1. A method of communicatively coupling power line communication (PLC)devices to a first and a second overhead power line conductor thattravel in a substantially parallel physical arrangement and in aspaced-apart relation, the method comprising: coupling a first PLCdevice to the first power line conductor at a first location; coupling asecond PLC device to the first power line conductor at a second locationfor communication with said first PLC device, at least in part, via thefirst power line conductor; coupling a third PLC device to the secondpower line conductor at a third location for communication with saidfirst PLC device; wherein the distance from said third location to saidfirst location is less than the distance from said first location tosaid second location; and wherein the distance from said third locationto said second location is less than the distance from said firstlocation to said second location.
 2. The method of claim 1, furthercomprising coupling a fourth PLC device to the second power lineconductor at a fourth location for communication with said first PLCdevice and wherein said fourth location is between said first locationand said second location.
 3. The method of claim 1, further comprisingcoupling a fourth PLC device to a third power line conductor at a fourthlocation for communication with said first PLC device and wherein saidfourth location is between said first location and said second location.4. The method of claim 1, wherein said third PLC device forms part of adata path bypassing a transformer.
 5. The method of claim 1, whereinsaid first PLC device comprises a backhaul device.
 6. The method ofclaim 1, wherein said first PLC device forms part of a data path betweenthe second PLC device and the Internet.
 7. The method of claim 1,wherein said first PLC device comprises a first modem.
 8. The method ofclaim 7, wherein said first PLC device further comprises a router incommunication with said first modem.
 9. The method of claim 7, whereinsaid first PLC device further comprises a wireless transceiver incommunication with said first modem.
 10. The method of claim 7, whereinsaid first PLC device is configured to perform media access controlprocessing.
 11. The method of claim 1, wherein the first and secondpower line conductors carry different phases of a power signal.
 12. Themethod of claim 1, wherein the first and second power line conductorscarry voltages greater than one thousand volts.
 13. The method of claim1, wherein said first PLC device is coupled to the first conductor atsaid first location by attaching a coupler that couples via inductance.14. The method of claim 13, wherein said coupler comprises asubstantially toroidal shaped core disposed substantially around theentire circumference of the first conductor.
 15. The method of claim 1,wherein said first PLC device is coupled to the first conductor at saidfirst location by attaching a coupler that couples via capacitance. 16.The method of claim 1, wherein said third PLC device communicates withsaid second PLC device.
 17. A power line communication (PLC) system foruse with a first and second power line overhead conductor that travel ina substantially parallel physical arrangement and in a spaced-apartrelation, comprising: a first PLC device coupled to the first power lineconductor at a first location; a second PLC device coupled to the firstpower line conductor at a second location and in communication with saidfirst PLC device, at least in part, via the first power line conductor;a third PLC device coupled to the second power line conductor at a thirdlocation and in communication with said first PLC device; and whereinsaid third location is between said first location and said secondlocation.
 18. The system of claim 17, further comprising a fourth PLCdevice coupled to the second power line conductor between said firstlocation and said second location and in communication with said firstPLC device.
 19. The system of claim 17, further comprising a fourth PLCdevice coupled to a third power line conductor between said firstlocation and said second location and in communication with said firstPLC device.
 20. The system of claim 17, wherein said third PLC deviceforms part of a data path bypassing a transformer.
 21. The system ofclaim 17, wherein said first PLC device comprises a backhaul device. 22.The system of claim 17, wherein said first PLC device forms part of adata path between the second PLC device and the Internet.
 23. The systemof claim 17, wherein said first PLC device comprises a first modem. 24.The system of claim 23, wherein said first PLC device further comprisesa router in communication with said first modem.
 25. The system of claim23, wherein said first PLC device further comprises a wirelesstransceiver in communication with said first modem.
 26. The system ofclaim 17, wherein said first PLC device is configured to perform mediaaccess control processing.
 27. A method of communicatively couplingpower line communication (PLC) devices to a first and second overheadpower line conductor that travel in a substantially parallel physicalarrangement and in spaced-apart relation, the method comprising:coupling a first PLC device to the first power line conductor at a firstlocation; coupling a second PLC device to the first power line conductorat a second location for communication with said first PLC device, atleast in part, via the first power line conductor; coupling a third PLCdevice to the second power line conductor at a third location forcommunication with said first PLC device; and wherein said thirdlocation is between said first location and said second location.
 28. Amethod of communicating data between a first, second, and third PLCdevice in which the first and second PLC devices are coupled to a firstoverhead power line conductor and the third PLC device is coupled to asecond overhead power line conductor and wherein the first and secondoverhead power line conductors travel in a substantially parallelphysical arrangement and in a spaced-apart relation, the methodcomprising: transmitting a first data signal along the first overheadconductor from the first PLC device; receiving the first data signalfrom the first overhead conductor at the second PLC device; transmittinga second data signal along the first overhead conductor from the firstPLC device; receiving the second data signal from second overheadconductor at the third PLC device; and wherein the second data signalcouples from the first overhead conductor to the second overheadconductor, at least in part, through the air.
 29. A method ofcommunicating data between a first and a second PLC device that arecoupled to first and second overhead power line conductors,respectively, and wherein the first and second overhead power lineconductors travel in a substantially parallel physical arrangement andin a spaced-apart relation, the method comprising: transmitting a firstdata signal including first data along the first overhead conductor fromthe first PLC; receiving the first data signal from second overheadconductor at the second PLC device; wherein the first data signalcouples from the first overhead conductor to the second overheadconductor, at least in part, through air; and transmitting the firstdata from the second PLC device to a user device disposed at a customerpremises.
 30. The method of claim 29, further comprising: transmitting asecond data signal along the second overhead conductor from the secondPLC device; receiving the second data signal from the first overheadconductor at the first PLC device; and wherein the second data signalcouples from the second overhead conductor to the first overheadconductor, at least in part, through air.
 31. The method of claim 29,wherein the data signal is comprised of at least one carrier at afrequency greater than one megahertz.
 32. The method of claim 29, wherein the data signal is comprised of at least one carrier at a frequencygreater than four megahertz.
 33. The method of claim 29, where in thedata signal is comprised of at least one carrier at a frequency greaterthan twenty megahertz.
 34. The method of claim 29, further comprisingmodulating and demodulating the first data signal at the second PLCdevice.
 35. The method of claim 31, wherein: the first data signal isreceived in a first frequency range; and wherein the second PLC devicetransmits the first data in a second freuuency range; and wherein thefirst frequency range is different than the second frequency range. 36.The method of claim 35, wherein the first frequency range does notoverlap with the second frequency range.
 37. The method of claim 29,wherein said transmitting of the first data by the second PLC deviceincludes transmitting the first data on a low voltage power line. 38.The method of claim 37, further comprising routing the first data at thesecond PLC device.
 39. The method of claim 29, wherein said first datasignal comprises power usage data.
 40. The method of claim 29, whereinsaid first data signal comprises to voice data.
 41. The method of claim29, further comprising periodically measuring voltage on a low-voltagepower line at the second PLC device.
 42. The method of claim 29, furthercomprising performing media access control processing at the second PLCdevice.
 43. A method of communicating a data signal including data on anoverhead three-phase medium voltage electrical system that includesthree phases that travel in a substantially parallel physicalarrangement and in a spaced-apart relation, comprising: transmittingsaid data signal on a first phase of the electrical system; receivingsaid data signal on a second phase of the electrical system; whereinsaid data signal is comprised of a carrier at a frequency of at leastone megahertz; wherein said data signal couples between the first andsecond phase conductors of the electrical system, at least in part,through the air; and transmitting the data from the second phase to auser device disposed at a customer premises.
 44. The method of claim 43,further comprising receiving said data signal on a third phase of theelectrical system, wherein the data signal couples between the first andthird phases of the electrical system.
 45. The method of claim 43,further comprising receiving said data signal on a third phase of theelectrical system, wherein the data signal couples between the secondand third phases of the electrical system.
 46. The method of claim 43,wherein said data signal is comprised of carrier of at least twentymegahertz.